Korean War

For other conflicts and wars involving Korea, see List of Korean battles.

For the ongoing conflict, see Korean conflict.

The Korean War (in South Korean Hangul: 한국전쟁; hanja: 韓國戰爭; RR: Hanguk Jeonjaeng, "Korean War"; in North Korean Chosŏn'gŭl: 조국해방전쟁; hancha: 祖國解放戰爭; MR: Choguk haebang chǒnjaeng, "Fatherland Liberation War"; 25 June 1950 – 27 July 1953) began when North Korea invaded South Korea. The United Nations, with the United States as the principal force, came to the aid of South Korea. China came to the aid of North Korea, and the Soviet Union gave some assistance.

Korea was ruled by Japan from 1910 until the closing days of World War II. In August 1945, the Soviet Union declared war on Japan, as a result of an agreement with the United States, and liberated Korea north of the 38th parallel. U.S. forces subsequently moved into the south. By 1948, as a product of the Cold War between the Soviet Union and the United States, Korea was split into two regions, with separate governments. Both governments claimed to be the legitimate government of all of Korea, and neither side accepted the border as permanent. The conflict escalated into open warfare when North Korean forces—supported by the Soviet Union and China—moved into the south on 25 June 1950. On that day, the United Nations Security Council recognized this North Korean act as invasion and called for an immediate ceasefire. On 27 June, the Security Council adopted S/RES/83: Complaint of aggression upon the Republic of Korea and decided the formation and dispatch of the UN Forces in Korea. Twenty-one countries of the United Nations eventually contributed to the UN force, with the United States providing 88% of the UN's military personnel.

After the first two months of war, South Korean forces were on the point of defeat, forced back to the Pusan Perimeter. In September 1950, an amphibious UN counter-offensive was launched at Inchon, and cut off many North Korean troops. Those who escaped envelopment and capture were rapidly forced back north all the way to the border with China at the Yalu River, or into the mountainous interior. At this point, in October 1950, Chinese forces crossed the Yalu and entered the war. Chinese intervention triggered a retreat of UN forces which continued until mid-1951.

After these reversals of fortune, which saw Seoul change hands four times, the last two years of fighting became a war of attrition, with the front line close to the 38th parallel. The war in the air, however, was never a stalemate. North Korea was subject to a massive bombing campaign. Jet fighters confronted each other in air-to-air combat for the first time in history, and Soviet pilots covertly flew in defense of their communist allies.

The fighting ended on 27 July 1953, when an armistice was signed. The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners. However, no peace treaty has been signed, and the two Koreas are technically still at war. Periodic clashes, many of which are deadly, continue to the present.

Names

Korean War
South Korean name
Hangul	한국전쟁
Transcriptions Revised Romanization Hanguk Jeonjaeng McCune–Reischauer Han'guk Chŏnjaeng
North Korean name
Chosŏn'gŭl	조선전쟁
Transcriptions Revised Romanization Joseon Jeonjaeng McCune–Reischauer Chosŏn Chŏnjaeng

In the U.S., the war was initially described by President Harry S. Truman as a "police action" as it was an undeclared military action, conducted under the auspices of the United Nations. It has been referred to in the English-speaking world as "The Forgotten War" or "The Unknown War" because of the lack of public attention it received both during and after the war, and in relation to the global scale of World War II, which preceded it, and the subsequent angst of the Vietnam War, which succeeded it.

In South Korea, the war is usually referred to as "625" or the "6–2–5 Upheaval" (6.25 동란 (動亂), yook-i-o dongnan), reflecting the date of its commencement on 25 June.

In North Korea, the war is officially referred to as the "Fatherland Liberation War" (Choguk haebang chǒnjaeng) or alternatively the "Chosǒn [Korean] War" (조선전쟁, Chosǒn chǒnjaeng).

In China, the war is officially called the "War to Resist U.S. Aggression and Aid Korea" (simplified Chinese: 抗美援朝战争; traditional Chinese: 抗美援朝戰爭; pinyin: Kàngměiyuáncháo zhànzhēng), although the term "Chaoxian (Korean) War" (simplified Chinese: 朝鲜战争; traditional Chinese: 朝鮮戰爭; pinyin: Cháoxiǎn zhànzhēng) is also used in unofficial contexts, along with the term "Han (Korean) War" (simplified Chinese: 韩战; traditional Chinese: 韓戰; pinyin: Hán Zhàn) more commonly used in regions such as Hong Kong and Macau.

Background

Imperial Japanese rule (1910–1945)

Main article: Korea under Japanese rule

Japan destroyed the influence of China over Korea in the First Sino-Japanese War (1894–95), ushering in the short-lived Korean Empire. A decade later, after defeating Imperial Russia in the Russo-Japanese War (1904–05), Japan made Korea its protectorate with the Eulsa Treaty in 1905, then annexed it with the Japan–Korea Annexation Treaty in 1910.

Many Korean nationalists fled the country. A Provisional Government of the Republic of Korea was founded in 1919 in Nationalist China. It failed to achieve international recognition, failed to unite nationalist groups, and had a fractious relationship with its American-based founding President, Syngman Rhee. From 1919 to 1925 and beyond, Korean communists led internal and external warfare against the Japanese.

Korea was considered to be part of the Empire of Japan as an industrialized colony along with Taiwan, and both were part of the Greater East Asia Co-Prosperity Sphere. In 1937, the colonial Governor-General, General Jirō Minami, commanded the attempted cultural assimilation of Korea's 23.5 million people by banning the use and study of Korean language, literature, and culture, to be replaced with that of mandatory use and study of their Japanese counterparts. Starting in 1939, the populace was required to use Japanese names under the Sōshi-kaimei policy. Conscription of Koreans for labor in war industries began in 1939, with as many as 2 million Koreans conscripted into either the Japanese Army or into the Japanese labor force.

In China, the Nationalist National Revolutionary Army and the communist People's Liberation Army helped organize Korean refugees against the Japanese military, which had also occupied parts of China. The Nationalist-backed Koreans, led by Yi Pom-Sok, fought in the Burma Campaign (December 1941 – August 1945). The communists, led by Kim Il-sung among others, fought the Japanese in Korea and Manchuria.

At the Cairo Conference in November 1943, China, the United Kingdom, and United States all decided "in due course Korea shall become free and independent".

Soviet-Japanese War (1945)

Main article: Soviet-Japanese War (1945)

At the Tehran Conference in November 1943 and the Yalta Conference in February 1945, the Soviet Union promised to join its allies in the Pacific War within three months of the victory in Europe. Accordingly, it declared war on Japan on 9 August 1945, three days after the USA dropped the bomb on Hiroshima. By 10 August, the Red Army had begun to occupy the northern part of the Korean peninsula.

On the night of 10 August in Washington, American Colonels Dean Rusk and Charles H. Bonesteel III were tasked with dividing the Korean Peninsula into Soviet and U.S. occupation zones and proposed the 38th parallel. This was incorporated into America's General Order No. 1 which responded to the Japanese surrender on 15 August. Explaining the choice of the 38th parallel, Rusk observed, "even though it was further north than could be realistically reached by U.S. forces, in the event of Soviet disagreement ... we felt it important to include the capital of Korea in the area of responsibility of American troops". He noted that he was "faced with the scarcity of US forces immediately available, and time and space factors, which would make it difficult to reach very far north, before Soviet troops could enter the area". As Rusk's comments indicate, the Americans doubted whether the Soviet government would agree to this. Stalin, however, maintained his wartime policy of co-operation, and on 16 August the Red Army halted at the 38th parallel for three weeks to await the arrival of U.S. forces in the south.

Korea divided (1945–1949)

See also: Division of Korea

U.S. troops in Korea, September 1945

On 8 September 1945, U.S. Lt. Gen. John R. Hodge arrived in Incheon to accept the Japanese surrender south of the 38th parallel. Appointed as military governor, General Hodge directly controlled South Korea as head of the United States Army Military Government in Korea (USAMGIK 1945–48). He attempted to establish control by restoring Japanese colonial administrators to power, but in the face of Korean protests he quickly reversed this decision. The USAMGIK refused to recognize the provisional government of the short-lived People's Republic of Korea (PRK) due to its suspected Communist sympathies.

In December 1945, Korea was administered by a U.S.-Soviet Union Joint Commission, as agreed at the Moscow Conference, with the aim of granting independence after a five-year trusteeship. The idea was not popular among Koreans and riots broke out. To contain them, the USAMGIK banned strikes on 8 December 1945 and outlawed the PRK Revolutionary Government and the PRK People's Committees on 12 December 1945.

South Korean citizens protest Allied trusteeship in December 1945.

The right-wing Representative Democratic Council, led by Syngman Rhee, who had arrived with the U.S. military, opposed the trusteeship, arguing that Korea had already suffered from foreign occupation far too long. General Hodge began to distance himself from the proposal, even though it had originated with his government.

On 23 September 1946, an 8,000-strong railroad worker strike began in Pusan. Civil disorder spread throughout the country in what became known as the Autumn uprising. On 1 October 1946, Korean police killed three students in the Daegu Uprising; protesters counter-attacked, killing 38 policemen. On 3 October, some 10,000 people attacked the Yeongcheon police station, killing three policemen and injuring some 40 more; elsewhere, some 20 landlords and pro-Japanese South Korean officials were killed. The USAMGIK declared martial law.

Citing the inability of the Joint Commission to make progress, the U.S. government decided to hold an election under United Nations auspices with the aim of creating an independent Korea. The Soviet authorities and the Korean Communists refused to co-operate on the grounds it would not be fair, and many South Korean politicians boycotted it. A general election was held in the South on 10 May 1948. It was marred by political violence and sabotage resulting in 600 deaths. North Korea held parliamentary elections three months later on 25 August.

Jeju residents awaiting execution in May 1948

The resultant South Korean government promulgated a national political constitution on 17 July 1948, and elected Syngman Rhee as President on 20 July 1948. The Republic of Korea (South Korea) was established on 15 August 1948. In the Russian Korean Zone of Occupation, the Soviet Union established a communist government led by Kim Il-sung. President Rhee's régime excluded communists and leftists from southern politics. Disenfranchised, they headed for the hills, to prepare for guerrilla war against the US-sponsored ROK government.

Meanwhile, on 3 April 1948, what began as a demonstration commemorating Korean resistance to Japanese rule ended with the Jeju uprising where between 14,000 and 60,000 people died. South Korean Army soldiers carried out large-scale atrocities during its suppression of the uprising. In October 1948, some South Korean soldiers mutinied against the clampdown in the Yeosu-Suncheon Rebellion.

The Soviet Union withdrew as agreed from Korea in 1948, and U.S. troops withdrew in 1949. On 24 December 1949, South Korean forces killed 86 to 88 people in the Mungyeong massacre and blamed the crime on marauding communist bands. By early 1950, Syngman Rhee had about 30,000 alleged communists in jails and about 300,000 suspected sympathizers enrolled in the Bodo League re-education movement.

Chinese Civil War (1945–1949)

Main article: Chinese Civil War

With the end of the war with Japan, the Chinese Civil War resumed between the Chinese Communists and the Chinese Nationalists. While the Communists were struggling for supremacy in Manchuria, they were supported by the North Korean government with matériel and manpower. According to Chinese sources, the North Koreans donated 2,000 railway cars worth of matériel while thousands of Koreans served in the Chinese People's Liberation Army (PLA) during the war. North Korea also provided the Chinese Communists in Manchuria with a safe refuge for non-combatants and communications with the rest of China.

The North Korean contributions to the Chinese Communist victory were not forgotten after the creation of the People's Republic of China in 1949. As a token of gratitude, between 50,000 and 70,000 Korean veterans that served in the PLA were sent back along with their weapons, and they later played a significant role in the initial invasion of South Korea. China promised to support the North Koreans in the event of a war against South Korea. The Chinese support created a deep division between the Korean Communists, and Kim Il-sung's authority within the Communist party was challenged by the Chinese faction led by Pak Il-yu, who was later purged by Kim.

After the formation of the People's Republic of China in 1949, the Chinese government named the Western nations, led by the United States, as the biggest threat to its national security. Basing this judgment on China's century of humiliation beginning in the early 19th century, American support for the Nationalists during the Chinese Civil War, and the ideological struggles between revolutionaries and reactionaries, the Chinese leadership believed that China would become a critical battleground in the United States' crusade against Communism. As a countermeasure and to elevate China's standing among the worldwide Communist movements, the Chinese leadership adopted a foreign policy that actively promoted Communist revolutions throughout territories on China's periphery.

Course of the war

The outbreak of war (1950)

Territory often changed hands early in the war, until the front stabilized.
 • North Korean and Chinese forces
 • South Korean, American, Commonwealth and United Nations forces

By 1949, South Korean forces had reduced the active number of communist guerrillas in the South from 5,000 to 1,000. However, Kim Il-sung believed that the guerrillas weakened the South Korean military and that a North Korean invasion would be welcomed by much of the South Korean population. Kim began seeking Stalin's support for an invasion in March 1949, traveling to Moscow to attempt to persuade him.

Stalin initially did not think the time was right for a war in Korea. Chinese Communist forces were still fighting in China. American forces were still stationed in South Korea (they would complete their withdrawal in June 1949) and Stalin did not want the Soviet Union to become embroiled in a war with the United States. By Spring 1950, he believed that the strategic situation had changed. The Soviets detonated their first nuclear bomb in September 1949; American soldiers fully withdrew from Korea; the Americans did not intervene to stop the communist victory in China, and Stalin calculated that the Americans would be even less willing to fight in Korea—which had seemingly much less strategic significance. The Soviets had also cracked the codes used by the US to communicate with the US embassy in Moscow, and reading these dispatches convinced Stalin that Korea did not have the importance to the US that would warrant a nuclear confrontation. Stalin began a more aggressive strategy in Asia based on these developments, including promising economic and military aid to China through the Sino–Soviet Friendship, Alliance, and Mutual Assistance Treaty.

Throughout 1949 and 1950, the Soviets continued arming North Korea. After the Communist victory in the Chinese Civil War, ethnic Korean units in the Chinese People's Liberation Army (PLA) were released to North Korea. The combat veterans from China, the tanks, artillery and aircraft supplied by the Soviets, and rigorous training increased North Korea's military superiority over the South, armed by the US military with mostly small arms and given no heavy weaponry such as tanks.

In April 1950, Stalin gave Kim permission to invade the South under the condition that Mao would agree to send reinforcements if needed. Stalin made it clear that Soviet forces would not openly engage in combat, to avoid a direct war with the Americans. Kim met with Mao in May 1950. Mao was concerned the Americans would intervene but agreed to support the North Korean invasion. China desperately needed the economic and military aid promised by the Soviets. At that time, the Chinese were in the process of demobilizing half of the PLA's 5.6 million soldiers. However, Mao sent more ethnic Korean PLA veterans to Korea and promised to move an army closer to the Korean border. Once Mao's commitment was secured, preparations for war accelerated.

Soviet generals with extensive combat experience from the Second World War were sent to North Korea as the Soviet Advisory Group. These generals completed the plans for the attack by May. The original plans called for a skirmish to be initiated in the Ongjin Peninsula on the west coast of Korea. The North Koreans would then launch a "counterattack" that would capture Seoul and encircle and destroy the South Korean army. The final stage would involve destroying South Korean government remnants, capturing the rest of South Korea, including the ports.

On 7 June 1950, Kim Il-sung called for a Korea-wide election on 5–8 August 1950 and a consultative conference in Haeju on 15–17 June 1950. On 11 June, the North sent three diplomats to the South as a peace overture that Rhee rejected outright. On 21 June, Kim Il-Sung revised his war plan to involve a general attack across the 38th parallel, rather than a limited operation in the Ongjin peninsula. Kim was concerned that South Korean agents learned about the plans and South Korean forces were strengthening their defenses. Stalin agreed to this change of plan.

While these preparations were underway in the North, there were frequent clashes along the 38th parallel, especially at Kaesong and Ongjin, many initiated by the South. The Republic of Korea Army (ROK Army) was being trained by the U.S. Korean Military Advisory Group (KMAG). On the eve of war, KMAG's commander General William Lynn Roberts voiced utmost confidence in the ROK Army and boasted that any North Korean invasion would merely provide "target practice". For his part, Syngman Rhee repeatedly expressed his desire to conquer the North, including when American diplomat John Foster Dulles visited Korea on 18 June.

Although some South Korean and American intelligence officers predicted an attack from the North, similar predictions were made before and nothing happened. The Central Intelligence Agency noted the southward movement by the Korean People's Army (KPA), but assessed this as a "defensive measure" and concluded an invasion was "unlikely". On 23 June, UN observers inspected the border and did not detect that war was imminent.

A U.S. Air Force C-54 Skymaster transport burning in South Korea in June 1950. North Korean fighters destroyed a C-54 at Kimpo airfield on 25 June

At dawn on Sunday, 25 June 1950, the Korean People's Army crossed the 38th parallel behind artillery fire. The KPA justified its assault with the claim that ROK troops attacked first, and were aiming to arrest and execute the "bandit traitor Syngman Rhee". Fighting began on the strategic Ongjin peninsula in the west. There were initial South Korean claims that they captured the city of Haeju, and this sequence of events has led some scholars to argue that the South Koreans fired first.

Whoever fired the first shots in Ongjin, within an hour, North Korean forces attacked all along the 38th parallel. The North Koreans had a combined arms force including tanks supported by heavy artillery. The South Koreans had no tanks, anti-tank weapons or heavy artillery, to stop such an attack. In addition, South Koreans committed their forces in a piecemeal fashion and these were routed in a few days.

On 27 June, Rhee evacuated from Seoul with some of the government. On 28 June, at 2 am, the South Korean Army blew up the highway Hangang Bridge across the Han River in an attempt to stop the North Korean army. The bridge was detonated while 4,000 refugees were crossing it and hundreds were killed. Destroying the bridge also trapped many South Korean military units north of the Han River. In spite of such desperate measures, Seoul fell that same day. A number of South Korean National Assemblymen remained in Seoul when it fell, and forty-eight subsequently pledged allegiance to the North.

On 28 June, Rhee ordered the massacre of suspected political opponents in his own country.

In five days, the South Korean forces, which had 95,000 men on 25 June, was down to less than 22,000 men. In early July, when U.S. forces arrived, what was left of the South Korean forces were placed under U.S. operational command of the United Nations Command.

Hundreds of thousands of South Koreans fled south in mid-1950 after the North Korean army invaded

Factors in U.S. intervention

The Truman administration was unprepared for the invasion. Korea was not included in the strategic Asian Defense Perimeter outlined by Secretary of State Dean Acheson. Military strategists were more concerned with the security of Europe against the Soviet Union than East Asia. At the same time, the Administration was worried that a war in Korea could quickly widen into another world war should the Chinese or Soviets decide to get involved.

One facet of the changing attitude toward Korea and whether to get involved was Japan. Especially after the fall of China to the Communists, U.S. East Asian experts saw Japan as the critical counterweight to the Soviet Union and China in the region. While there was no United States policy dealing with South Korea directly as a national interest, its proximity to Japan increased the importance of South Korea. Said Kim: "The recognition that the security of Japan required a non-hostile Korea led directly to President Truman's decision to intervene ... The essential point ... is that the American response to the North Korean attack stemmed from considerations of U.S. policy toward Japan." A major consideration was the possible Soviet reaction in the event that the U.S. intervened. The Truman administration was fretful that a war in Korea was a diversionary assault that would escalate to a general war in Europe once the United States committed in Korea. At the same time, "[t]here was no suggestion from anyone that the United Nations or the United States could back away from [the conflict]". Yugoslavia–a possible Soviet target because of the Tito–Stalin Split—was vital to the defense of Italy and Greece, and the country was first on the list of the National Security Council's post-North Korea invasion list of "chief danger spots". Truman believed if aggression went unchecked, a chain reaction would be initiated that would marginalize the United Nations and encourage Communist aggression elsewhere. The UN Security Council approved the use of force to help the South Koreans and the U.S. immediately began using what air and naval forces that were in the area to that end. The Administration still refrained from committing on the ground because some advisers believed the North Koreans could be stopped by air and naval power alone.

The Truman administration was still uncertain if the attack was a ploy by the Soviet Union or just a test of U.S. resolve. The decision to commit ground troops became viable when a communiqué was received on 27 June indicating the Soviet Union would not move against U.S. forces in Korea. The Truman administration now believed it could intervene in Korea without undermining its commitments elsewhere.

United Nations Security Council Resolutions

Further information: List of United Nations Security Council resolutions concerning North Korea

On 25 June 1950, the United Nations Security Council unanimously condemned the North Korean invasion of the Republic of Korea, with UN Security Council Resolution 82. The Soviet Union, a veto-wielding power, had boycotted the Council meetings since January 1950, protesting that the Republic of China (Taiwan), not the People's Republic of China, held a permanent seat in the UN Security Council. After debating the matter, the Security Council, on 27 June 1950, published Resolution 83 recommending member states provide military assistance to the Republic of Korea. On 27 June President Truman ordered U.S. air and sea forces to help the South Korean regime. On 4 July the Soviet Deputy Foreign Minister accused the United States of starting armed intervention on behalf of South Korea.

The Soviet Union challenged the legitimacy of the war for several reasons. The ROK Army intelligence upon which Resolution 83 was based came from U.S. Intelligence; North Korea was not invited as a sitting temporary member of the UN, which violated UN Charter Article 32; and the fighting was beyond the UN Charter's scope, because the initial north–south border fighting was classed as a civil war. Because the Soviet Union was boycotting the Security Council at the time, legal scholars posited that deciding upon an action of this type required the unanimous vote of all the six permanent members including the Soviet Union.

Comparison of military forces

In early 1951 USAF recruits arrived by the train load, more than doubling the population of Lackland AFB in San Antonio, Texas

By mid-1950, North Korean forces numbered between 150,000 and 200,000 troops, organized into 10 infantry divisions, one tank division, and one air force division, with 210 fighter planes and 280 tanks, who captured scheduled objectives and territory, among them Kaesong, Chuncheon, Uijeongbu, and Ongjin. Their forces included 274 T-34-85 tanks, 200 artillery pieces, 110 attack bombers, some 150 Yak fighter planes, 78 Yak trainers, and 35 reconnaissance aircraft. In addition to the invasion force, the North KPA had 114 fighters, 78 bombers, 105 T-34-85 tanks, and some 30,000 soldiers stationed in reserve in North Korea. Although each navy consisted of only several small warships, the North and South Korean navies fought in the war as sea-borne artillery for their armies.

In contrast, the ROK Army defenders were unprepared and ill-equipped. As of 25 June 1950 the ROK Army had 98,000 soldiers (65,000 combat, 33,000 support), no tanks (they had been requested from the U.S. military, but requests were denied), and a 22-piece air force comprising 12 liaison-type and 10 AT6 advanced-trainer airplanes. There were no large foreign military garrisons in Korea at the time of the invasion, but there were large U.S. garrisons and air forces in Japan.

Within days of the invasion, masses of ROK Army soldiers—of dubious loyalty to the Syngman Rhee regime—were retreating southwards or defecting en masse to the northern side, the KPA.

United Nations' response (July – August 1950)

A U.S. howitzer position near the Kum River, 15 July

On Saturday, 24 June 1950, U.S. Secretary of State Dean Acheson informed President Truman that the North Koreans had invaded South Korea. Truman and Acheson discussed a U.S. invasion response and agreed that the United States was obligated to act, paralleling the North Korean invasion with Adolf Hitler's aggressions in the 1930s, with the conclusion being that the mistake of appeasement must not be repeated. Several U.S. industries were mobilized to supply materials, labor, capital, production facilities, and other services necessary to support the military objectives of the Korean War. However, President Truman later acknowledged that he believed fighting the invasion was essential to the American goal of the global containment of communism as outlined in the National Security Council Report 68 (NSC-68) (declassified in 1975):

Communism was acting in Korea, just as Hitler, Mussolini and the Japanese had ten, fifteen, and twenty years earlier. I felt certain that if South Korea was allowed to fall, Communist leaders would be emboldened to override nations closer to our own shores. If the Communists were permitted to force their way into the Republic of Korea without opposition from the free world, no small nation would have the courage to resist threat and aggression by stronger Communist neighbors.

G.I. comforting a grieving infantryman

In August 1950, the President and the Secretary of State obtained the consent of Congress to appropriate $12 billion for military action in Korea.

As an initial response, Truman called for a naval blockade of North Korea, and was shocked to learn that such a blockade could be imposed only "on paper", since the U.S. Navy no longer had the warships with which to carry out his request. In fact, because of the extensive defense cuts and the emphasis placed on building a nuclear bomber force, none of the services were in a position to make a robust response with conventional military strength. General Omar Bradley, Chairman of the Joint Chiefs of Staff, was faced with re-organizing and deploying an American military force that was a shadow of its World War II counterpart. The impact of the Truman administration's defense budget cutbacks were now keenly felt, as American troops fought a series of costly rearguard actions. Lacking sufficient anti-tank weapons, artillery or armor, they were driven back down the Korean peninsula to Pusan. In a postwar analysis of the unpreparedness of U.S. Army forces deployed to Korea during the summer and fall of 1950, Army Major General Floyd L. Parks stated that "Many who never lived to tell the tale had to fight the full range of ground warfare from offensive to delaying action, unit by unit, man by man ... [T]hat we were able to snatch victory from the jaws of defeat ... does not relieve us from the blame of having placed our own flesh and blood in such a predicament."

Acting on State Secretary Acheson's recommendation, President Truman ordered General MacArthur to transfer matériel to the Army of the Republic of Korea while giving air cover to the evacuation of U.S. nationals. The President disagreed with advisers who recommended unilateral U.S. bombing of the North Korean forces, and ordered the US Seventh Fleet to protect the Republic of China (Taiwan), whose government asked to fight in Korea. The United States denied ROC's request for combat, lest it provoke a communist Chinese retaliation. Because the United States had sent the Seventh Fleet to "neutralize" the Taiwan Strait, Chinese premier Zhou Enlai criticized both the UN and U.S. initiatives as "armed aggression on Chinese territory".

Crew of an M-24 tank along the Nakdong River front, August 1950

The Battle of Osan, the first significant American engagement of the Korean War, involved the 540-soldier Task Force Smith, which was a small forward element of the 24th Infantry Division which had been flown in from Japan. On 5 July 1950, Task Force Smith attacked the North Koreans at Osan but without weapons capable of destroying the North Koreans' tanks. They were unsuccessful; the result was 180 dead, wounded, or taken prisoner. The KPA progressed southwards, pushing back the US force at Pyongtaek, Chonan, and Chochiwon, forcing the 24th Division's retreat to Taejeon, which the KPA captured in the Battle of Taejon; the 24th Division suffered 3,602 dead and wounded and 2,962 captured, including the Division's Commander, Major General William F. Dean.

By August, the KPA pushed back the ROK Army and the Eighth United States Army to the vicinity of Pusan in southeast Korea. In their southward advance, the KPA purged the Republic of Korea's intelligentsia by killing civil servants and intellectuals. On 20 August, General MacArthur warned North Korean leader Kim Il-sung he was responsible for the KPA's atrocities. By September, the UN Command controlled the Pusan perimeter, enclosing about 10% of Korea, in a line partially defined by the Nakdong River.

Although Kim's early successes led him to predict he would end the war by the end of August, Chinese leaders were more pessimistic. To counter a possible U.S. deployment, Zhou Enlai secured a Soviet commitment to have the Soviet Union support Chinese forces with air cover, and deployed 260,000 soldiers along the Korean border, under the command of Gao Gang. Zhou commanded Chai Chengwen to conduct a topographical survey of Korea, and directed Lei Yingfu, Zhou's military advisor in Korea, to analyze the military situation in Korea. Lei concluded that MacArthur would most likely attempt a landing at Incheon. After conferring with Mao that this would be MacArthur's most likely strategy, Zhou briefed Soviet and North Korean advisers of Lei's findings, and issued orders to Chinese army commanders deployed on the Korean border to prepare for American naval activity in the Korea Strait.

Escalation (August – September 1950)

U.S. Air Force attacking railroads south of Wonsan on the eastern coast of North Korea

In the resulting Battle of Pusan Perimeter (August–September 1950), the U.S. Army withstood KPA attacks meant to capture the city at the Naktong Bulge, P'ohang-dong, and Taegu. The United States Air Force (USAF) interrupted KPA logistics with 40 daily ground support sorties that destroyed 32 bridges, halting most daytime road and rail traffic. KPA forces were forced to hide in tunnels by day and move only at night. To deny matériel to the KPA, the USAF destroyed logistics depots, petroleum refineries, and harbors, while the U.S. Navy air forces attacked transport hubs. Consequently, the over-extended KPA could not be supplied throughout the south. On 27 August, 67th Fighter Squadron aircraft mistakenly attacked facilities in Chinese territory and the Soviet Union called the UN Security Council's attention to China's complaint about the incident. The US proposed that a commission of India and Sweden determine what the US should pay in compensation but the Soviets vetoed the US proposal.

Meanwhile, U.S. garrisons in Japan continually dispatched soldiers and matériel to reinforce defenders in the Pusan Perimeter. Tank battalions deployed to Korea directly from the U.S. mainland from the port of San Francisco to the port of Pusan, the largest Korean port. By late August, the Pusan Perimeter had some 500 medium tanks battle-ready. In early September 1950, ROK Army and UN Command forces outnumbered the KPA 180,000 to 100,000 soldiers. The UN forces, once prepared, counterattacked and broke out of the Pusan Perimeter.

Battle of Inchon (September 1950)

Main article: Battle of Inchon

Against the rested and re-armed Pusan Perimeter defenders and their reinforcements, the KPA were undermanned and poorly supplied; unlike the UN Command, they lacked naval and air support. To relieve the Pusan Perimeter, General MacArthur recommended an amphibious landing at Incheon, near Seoul and well over 100 miles (160 km) behind the KPA lines. On 6 July, he ordered Major General Hobart R. Gay, Commander, 1st Cavalry Division, to plan the division's amphibious landing at Incheon; on 12–14 July, the 1st Cavalry Division embarked from Yokohama, Japan, to reinforce the 24th Infantry Division inside the Pusan Perimeter.

General Douglas MacArthur, UN Command CiC (seated), observes the naval shelling of Incheon from USS Mount McKinley, 15 September 1950

Soon after the war began, General MacArthur began planning a landing at Incheon, but the Pentagon opposed him. When authorized, he activated a combined U.S. Army and Marine Corps, and ROK Army force. The X Corps, led by General Edward Almond, Commander, consisted of 40,000 men of the 1st Marine Division, the 7th Infantry Division and around 8,600 ROK Army soldiers. By 15 September, the amphibious assault force faced few KPA defenders at Incheon: military intelligence, psychological warfare, guerrilla reconnaissance, and protracted bombardment facilitated a relatively light battle. However, the bombardment destroyed most of the city of Incheon.

After the Incheon landing, the 1st Cavalry Division began its northward advance from the Pusan Perimeter. "Task Force Lynch" (after Lieutenant Colonel James H. Lynch), 3rd Battalion, 7th Cavalry Regiment, and two 70th Tank Battalion units (Charlie Company and the Intelligence–Reconnaissance Platoon) effected the "Pusan Perimeter Breakout" through 106.4 miles (171.2 km) of enemy territory to join the 7th Infantry Division at Osan. The X Corps rapidly defeated the KPA defenders around Seoul, thus threatening to trap the main KPA force in Southern Korea.

On 18 September, Stalin dispatched General H. M. Zakharov to Korea to advise Kim Il-sung to halt his offensive around the Pusan perimeter and to redeploy his forces to defend Seoul. Chinese commanders were not briefed on North Korean troop numbers or operational plans. As the overall commander of Chinese forces, Zhou Enlai suggested that the North Koreans should attempt to eliminate the enemy forces at Incheon only if they had reserves of at least 100,000 men; otherwise, he advised the North Koreans to withdraw their forces north.

On 25 September, Seoul was recaptured by South Korean forces. American air raids caused heavy damage to the KPA, destroying most of its tanks and much of its artillery. North Korean troops in the south, instead of effectively withdrawing north, rapidly disintegrated, leaving Pyongyang vulnerable. During the general retreat only 25,000 to 30,000 soldiers managed to rejoin the Northern KPA lines. On 27 September, Stalin convened an emergency session of the Politburo, in which he condemned the incompetence of the KPA command and held Soviet military advisers responsible for the defeat.

UN forces cross partition line (September – October 1950)

Main article: UN Offensive, 1950

Combat in the streets of Seoul

On 27 September, MacArthur received the top secret National Security Council Memorandum 81/1 from Truman reminding him that operations north of the 38th parallel were authorized only if "at the time of such operation there was no entry into North Korea by major Soviet or Chinese Communist forces, no announcements of intended entry, nor a threat to counter our operations militarily". On 29 September MacArthur restored the government of the Republic of Korea under Syngman Rhee. On 30 September, Defense Secretary George Marshall sent an eyes-only message to MacArthur: "We want you to feel unhampered tactically and strategically to proceed north of the 38th parallel." During October, the ROK police executed people who were suspected to be sympathetic to North Korea, and similar massacres were carried out until early 1951.

On 30 September, Zhou Enlai warned the United States that China was prepared to intervene in Korea if the United States crossed the 38th parallel. Zhou attempted to advise North Korean commanders on how to conduct a general withdrawal by using the same tactics which allowed Chinese communist forces to successfully escape Chiang Kai-shek's Encirclement Campaigns in the 1930s, but by some accounts North Korean commanders did not utilize these tactics effectively. Historian Bruce Cumings argues, however, the KPA's rapid withdrawal was strategic, with troops melting into the mountains from where they could launch guerrilla raids on the UN forces spread out on the coasts.

By 1 October 1950, the UN Command repelled the KPA northwards past the 38th parallel; the ROK Army crossed after them, into North Korea. MacArthur made a statement demanding the KPA's unconditional surrender. Six days later, on 7 October, with UN authorization, the UN Command forces followed the ROK forces northwards. The X Corps landed at Wonsan (in southeastern North Korea) and Riwon (in northeastern North Korea), already captured by ROK forces. The Eighth U.S. Army and the ROK Army drove up western Korea and captured Pyongyang city, the North Korean capital, on 19 October 1950. The 187th Airborne Regimental Combat Team ("Rakkasans") made their first of two combat jumps during the Korean War on 20 October 1950 at Sunchon and Sukchon. The missions of the 187th were to cut the road north going to China, preventing North Korean leaders from escaping from Pyongyang; and to rescue American prisoners of war. At month's end, UN forces held 135,000 KPA prisoners of war. As they neared the Sino-Korean border, the UN forces in the west were divided from those in the east by 50–100 miles of mountainous terrain.

Taking advantage of the UN Command's strategic momentum against the communists, General MacArthur believed it necessary to extend the Korean War into China to destroy depots supplying the North Korean war effort. President Truman disagreed, and ordered caution at the Sino-Korean border.

China intervenes (October – December 1950)

Chinese forces cross the Yalu River

On 27 June 1950, two days after the KPA invaded and three months before the Chinese entered the war, President Truman dispatched the United States Seventh Fleet to the Taiwan Strait, to prevent hostilities between the Nationalist Republic of China (Taiwan) and the People's Republic of China (PRC). On 4 August 1950, with the PRC invasion of Taiwan aborted, Mao Zedong reported to the Politburo that he would intervene in Korea when the People's Liberation Army's (PLA) Taiwan invasion force was reorganized into the PLA North East Frontier Force. China justified its entry into the war as a response to "American aggression in the guise of the UN".

On 20 August 1950, Premier Zhou Enlai informed the UN that "Korea is China's neighbor ... The Chinese people cannot but be concerned about a solution of the Korean question". Thus, through neutral-country diplomats, China warned that in safeguarding Chinese national security, they would intervene against the UN Command in Korea. President Truman interpreted the communication as "a bald attempt to blackmail the UN", and dismissed it.

Three commanders of PVA during the Korean War. From left to right: Chen Geng (1952), Peng Dehuai (1950–1952) and Deng Hua (1952–1953)

1 October 1950, the day that UN troops crossed the 38th parallel, was also the first anniversary of the founding of the People's Republic of China. On that day the Soviet ambassador forwarded a telegram from Stalin to Mao and Zhou requesting that China send five to six divisions into Korea, and Kim Il-sung sent frantic appeals to Mao for Chinese military intervention. At the same time, Stalin made it clear that Soviet forces themselves would not directly intervene.

In a series of emergency meetings that lasted from 2 to 5 October, Chinese leaders debated whether to send Chinese troops into Korea. There was considerable resistance among many leaders, including senior military leaders, to confronting the U.S. in Korea. Mao strongly supported intervention, and Zhou was one of the few Chinese leaders who firmly supported him. After Lin Biao politely refused Mao's offer to command Chinese forces in Korea (citing his upcoming medical treatment), Mao decided that Peng Dehuai would be the commander of the Chinese forces in Korea after Peng agreed to support Mao's position. Mao then asked Peng to speak in favor of intervention to the rest of the Chinese leaders. After Peng made the case that if U.S. troops conquered Korea and reached the Yalu they might cross it and invade China the Politburo agreed to intervene in Korea. Later, the Chinese claimed that US bombers had violated PRC national airspace on three separate occasions and attacked Chinese targets before China intervened. On 8 October 1950, Mao Zedong redesignated the PLA North East Frontier Force as the Chinese People's Volunteer Army (PVA).

To enlist Stalin's support, Zhou and a Chinese delegation left for Moscow on 8 October, arriving there on 10 October at which point they flew to Stalin's home at the Black Sea. There they conferred with the top Soviet leadership which included Joseph Stalin as well as Vyacheslav Molotov, Lavrentiy Beria and Georgi Malenkov. Stalin initially agreed to send military equipment and ammunition, but warned Zhou that the Soviet Union's air force would need two or three months to prepare any operations. In a subsequent meeting, Stalin told Zhou that he would only provide China with equipment on a credit basis, and that the Soviet air force would only operate over Chinese airspace, and only after an undisclosed period of time. Stalin did not agree to send either military equipment or air support until March 1951. Mao did not find Soviet air support especially useful, as the fighting was going to take place on the south side of the Yalu. Soviet shipments of matériel, when they did arrive, were limited to small quantities of trucks, grenades, machine guns, and the like.

Immediately on his return to Beijing on 18 October 1950, Zhou met with Mao Zedong, Peng Dehuai, and Gao Gang, and the group ordered two hundred thousand Chinese troops to enter North Korea, which they did on 25 October. After consulting with Stalin, on 13 November, Mao appointed Zhou the overall commander and coordinator of the war effort, with Peng as field commander. Orders given by Zhou were delivered in the name of the Central Military Commission.

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A Soviet-built MiG 15 in North Korean markings. The arrival of MiGs challenged UN air superiority

UN aerial reconnaissance had difficulty sighting PVA units in daytime, because their march and bivouac discipline minimized aerial detection. The PVA marched "dark-to-dark" (19:00–03:00), and aerial camouflage (concealing soldiers, pack animals, and equipment) was deployed by 05:30. Meanwhile, daylight advance parties scouted for the next bivouac site. During daylight activity or marching, soldiers were to remain motionless if an aircraft appeared, until it flew away; PVA officers were under order to shoot security violators. Such battlefield discipline allowed a three-division army to march the 286 miles (460 km) from An-tung, Manchuria, to the combat zone in some 19 days. Another division night-marched a circuitous mountain route, averaging 18 miles (29 km) daily for 18 days.

Meanwhile, on 10 October 1950, the 89th Tank Battalion was attached to the 1st Cavalry Division, increasing the armor available for the Northern Offensive. On 15 October, after moderate KPA resistance, the 7th Cavalry Regiment and Charlie Company, 70th Tank Battalion captured Namchonjam city. On 17 October, they flanked rightwards, away from the principal road (to Pyongyang), to capture Hwangju. Two days later, the 1st Cavalry Division captured Pyongyang, the North's capital city, on 19 October 1950. Kim Il-sung and his government temporarily moved its capital to Sinuiju—although as UNC forces approached, the government again moved—this time to Kanggye.

On 15 October 1950, President Truman and General MacArthur met at Wake Island in the mid-Pacific Ocean. This meeting was much publicized because of the General's discourteous refusal to meet the President on the continental United States. To President Truman, MacArthur speculated there was little risk of Chinese intervention in Korea, and that the PRC's opportunity for aiding the KPA had lapsed. He believed the PRC had some 300,000 soldiers in Manchuria, and some 100,000–125,000 soldiers at the Yalu River. He further concluded that, although half of those forces might cross south, "if the Chinese tried to get down to Pyongyang, there would be the greatest slaughter" without air force protection.

After secretly crossing the Yalu River on 19 October, the PVA 13th Army Group launched the First Phase Offensive on 25 October, attacking the advancing UN forces near the Sino-Korean border. This military decision made solely by China changed the attitude of the Soviet Union. Twelve days after Chinese troops entered the war, Stalin allowed the Soviet Air Force to provide air cover, and supported more aid to China. After decimating the ROK II Corps at the Battle of Onjong, the first confrontation between Chinese and U.S. military occurred on 1 November 1950; deep in North Korea, thousands of soldiers from the PVA 39th Army encircled and attacked the U.S. 8th Cavalry Regiment with three-prong assaults—from the north, northwest, and west—and overran the defensive position flanks in the Battle of Unsan. The surprise assault resulted in the UN forces retreating back to the Ch'ongch'on River, while the Chinese unexpectedly disappeared into mountain hideouts following victory. It is unclear why the Chinese did not press the attack and follow up their victory.

Soldiers from the U.S. 2nd Infantry Division in action near the Ch'ongch'on River, 20 November 1950

The UN Command, however, were unconvinced that the Chinese openly intervened because of the sudden Chinese withdrawal. On 24 November, the Home-by-Christmas Offensive was launched with the U.S. Eighth Army advancing in northwest Korea, while the US X Corps attacked along the Korean east coast. But the Chinese were waiting in ambush with their Second Phase Offensive.

On 25 November at the Korean western front, the PVA 13th Army Group attacked and overran the ROK II Corps at the Battle of the Ch'ongch'on River, and then decimated the US 2nd Infantry Division on the UN forces' right flank. The UN Command retreated; the U.S. Eighth Army's retreat (the longest in US Army history) was made possible because of the Turkish Brigade's successful, but very costly, rear-guard delaying action near Kunuri that slowed the PVA attack for two days (27–29 November). On 27 November at the Korean eastern front, a U.S. 7th Infantry Division Regimental Combat Team (3,000 soldiers) and the U.S. 1st Marine Division (12,000–15,000 marines) were unprepared for the PVA 9th Army Group's three-pronged encirclement tactics at the Battle of Chosin Reservoir, but escaped under Air Force and X Corps support fire—albeit with some 15,000 collective casualties.

F4U-5 Corsairs provide close air support to U.S. Marines fighting Chinese forces, December 1950.

By 30 November, the PVA 13th Army Group managed to expel the U.S. Eighth Army from northwest Korea. Retreating from the north faster than they had counter-invaded, the Eighth Army crossed the 38th parallel border in mid December. UN morale hit rock bottom when commanding General Walton Walker of the U.S. Eighth Army was killed on 23 December 1950 in an automobile accident. In northeast Korea by 11 December, the U.S. X Corps managed to cripple the PVA 9th Army Group while establishing a defensive perimeter at the port city of Hungnam. The X Corps were forced to evacuate by 24 December in order to reinforce the badly depleted U.S. Eighth Army to the south.

Map of the UN retreat in the wake of Chinese intervention

During the Hungnam evacuation, about 193 shiploads of UN Command forces and matériel (approximately 105,000 soldiers, 98,000 civilians, 17,500 vehicles, and 350,000 tons of supplies) were evacuated to Pusan. The SS Meredith Victory was noted for evacuating 14,000 refugees, the largest rescue operation by a single ship, even though it was designed to hold 12 passengers. Before escaping, the UN Command forces razed most of Hungnam city, especially the port facilities; and on 16 December 1950, President Truman declared a national emergency with Presidential Proclamation No. 2914, 3 C.F.R. 99 (1953), which remained in force until 14 September 1978. The next day (17 December 1950) Kim Il-sung was deprived of the right of command of KPA by China. After that, the leading part of the war became the Chinese army.

Fighting around the 38th parallel (January – June 1951)

With Lieutenant-General Matthew Ridgway assuming the command of the U.S. Eighth Army on 26 December, the PVA and the KPA launched their Third Phase Offensive (also known as the "Chinese New Year's Offensive") on New Year's Eve of 1950. Utilizing night attacks in which UN Command fighting positions were encircled and then assaulted by numerically superior troops who had the element of surprise, the attacks were accompanied by loud trumpets and gongs, which fulfilled the double purpose of facilitating tactical communication and mentally disorienting the enemy. UN forces initially had no familiarity with this tactic, and as a result some soldiers panicked, abandoning their weapons and retreating to the south. The Chinese New Year's Offensive overwhelmed UN forces, allowing the PVA and KPA to conquer Seoul for the second time on 4 January 1951.

B-26 Invaders bomb logistics depots in Wonsan, North Korea, 1951

These setbacks prompted General MacArthur to consider using nuclear weapons against the Chinese or North Korean interiors, with the intention that radioactive fallout zones would interrupt the Chinese supply chains. However, upon the arrival of the charismatic General Ridgway, the esprit de corps of the bloodied Eighth Army immediately began to revive.

UN forces retreated to Suwon in the west, Wonju in the center, and the territory north of Samcheok in the east, where the battlefront stabilized and held. The PVA had outrun its logistics capability and thus were unable to press on beyond Seoul as food, ammunition, and matériel were carried nightly, on foot and bicycle, from the border at the Yalu River to the three battle lines. In late January, upon finding that the PVA had abandoned their battle lines, General Ridgway ordered a reconnaissance-in-force, which became Operation Roundup (5 February 1951). A full-scale X Corps advance proceeded, which fully exploited the UN Command's air superiority, concluding with the UN reaching the Han River and recapturing Wonju.

Following the failure of ceasefire negotiations in January, the United Nations General Assembly passed Resolution 498 on 1 February, condemning PRC as an aggressor, and called upon its forces to withdraw from Korea.

In early February, the South Korean 11th Division ran the operation to destroy the guerrillas and their sympathizer citizens in Southern Korea. During the operation, the division and police conducted the Geochang massacre and Sancheong-Hamyang massacre. In mid-February, the PVA counterattacked with the Fourth Phase Offensive and achieved initial victory at Hoengseong. But the offensive was soon blunted by the IX Corps positions at Chipyong-ni in the center. The U.S. 2nd Infantry "Warrior" Division's 23rd Regimental Combat Team and the French Battalion fought a short but desperate battle that broke the attack's momentum. The battle is sometimes known as the Gettysburg of the Korean War. 5,600 Korean, American, and French troops were surrounded on all sides by 25,000 Chinese. United Nations forces had previously retreated in the face of large Communist forces instead of getting cut off, but this time they stood and fought, and won.

U.S. Marines move out over rugged mountain terrain while closing with hostile North Korean forces

In the last two weeks of February 1951, Operation Roundup was followed by Operation Killer, carried out by the revitalized Eighth Army. It was a full-scale, battlefront-length attack staged for maximum exploitation of firepower to kill as many KPA and PVA troops as possible. Operation Killer concluded with I Corps re-occupying the territory south of the Han River, and IX Corps capturing Hoengseong. On 7 March 1951, the Eighth Army attacked with Operation Ripper, expelling the PVA and the KPA from Seoul on 14 March 1951. This was the city's fourth conquest in a year's time, leaving it a ruin; the 1.5 million pre-war population was down to 200,000, and people were suffering from severe food shortages.

On 1 March 1951, Mao sent a cable to Stalin, in which he emphasized the difficulties faced by Chinese forces and the need for air cover, especially over supply lines. Apparently impressed by the Chinese war effort, Stalin agreed to supply two air force divisions, three anti-aircraft divisions, and six thousand trucks. PVA troops in Korea continued to suffer severe logistical problems throughout the war. In late April Peng Dehuai sent his deputy, Hong Xuezhi, to brief Zhou Enlai in Beijing. What Chinese soldiers feared, Hong said, was not the enemy, but having no food, bullets, or trucks to transport them to the rear when they were wounded. Zhou attempted to respond to the PVA's logistical concerns by increasing Chinese production and improving supply methods, but these efforts were never sufficient. At the same time, large-scale air defense training programs were carried out, and the Chinese Air Force began participating in the war from September 1951 onward.

On 11 April 1951, Commander-in-Chief Truman relieved the controversial General MacArthur, the Supreme Commander in Korea. There were several reasons for the dismissal. MacArthur crossed the 38th parallel in the mistaken belief that the Chinese would not enter the war, leading to major allied losses. He believed that whether to use nuclear weapons should be his decision, not the President's. MacArthur threatened to destroy China unless it surrendered. While MacArthur felt total victory was the only honorable outcome, Truman was more pessimistic about his chances once involved in a land war in Asia, and felt a truce and orderly withdrawal from Korea could be a valid solution. MacArthur was the subject of congressional hearings in May and June 1951, which determined that he had defied the orders of the President and thus had violated the U.S. Constitution. A popular criticism of MacArthur was that he never spent a night in Korea, and directed the war from the safety of Tokyo.

MacArthur was relieved primarily from his determination to expand the war into China, which other officials believed would needlessly escalate a limited war and consume too many already overstretched resources. Despite MacArthur's claims that he was restricted to fighting a limited war when China was fighting all-out, congressional testimony revealed China was using restraint as much as the Americans were, as they were not using air power against front line troops, communication lines, ports, naval air forces, or staging bases in Japan, which had been crucial to the survival of UN forces in Korea. Simply fighting on the peninsula had already tied down significant portions of U.S. airpower; as Air Force chief of staff Hoyt Vandenberg said, 80-85% the tactical capacity, one-fourth of the strategic portion, and 20% of air defense forces of the United States were engaged in a single country. There was also fear that crossing into China would provoke the Soviet Union into entering the war; General Omar Bradley testified that there were 35 Russian divisions totaling some 500,000 troops in the Far East, which if sent into action with the approximately 85 Russian submarines in the vicinity of Korea, they could overwhelm U.S. forces and cut supply lines, as well as potentially assist China in taking over territory in Southeast Asia.

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British UN troops advance alongside a Centurion tank, March 1951

General Ridgway was appointed Supreme Commander, Korea; he regrouped the UN forces for successful counterattacks, while General James Van Fleet assumed command of the U.S. Eighth Army. Further attacks slowly depleted the PVA and KPA forces; Operations Courageous (23–28 March 1951) and Tomahawk (23 March 1951) were a joint ground and airborne infilltration meant to trap Chinese forces between Kaesong and Seoul. UN forces advanced to "Line Kansas", north of the 38th parallel. The 187th Airborne Regimental Combat Team's ("Rakkasans") second of two combat jumps was on Easter Sunday, 1951, at Munsan-ni, South Korea, codenamed Operation Tomahawk. The mission was to get behind Chinese forces and block their movement north. The 60th Indian Parachute Field Ambulance provided the medical cover for the operations, dropping an ADS and a surgical team and treating over 400 battle casualties apart from the civilian casualties that formed the core of their objective as the unit was on a humanitarian mission.

The Chinese counterattacked in April 1951, with the Fifth Phase Offensive, also known as the Chinese Spring Offensive, with three field armies (approximately 700,000 men). The offensive's first thrust fell upon I Corps, which fiercely resisted in the Battle of the Imjin River (22–25 April 1951) and the Battle of Kapyong (22–25 April 1951), blunting the impetus of the offensive, which was halted at the "No-name Line" north of Seoul. On 15 May 1951, the Chinese commenced the second impulse of the Spring Offensive and attacked the ROK Army and the U.S. X Corps in the east at the Soyang River. After initial success, they were halted by 20 May. At month's end, the U.S. Eighth Army counterattacked and regained "Line Kansas", just north of the 38th parallel. The UN's "Line Kansas" halt and subsequent offensive action stand-down began the stalemate that lasted until the armistice of 1953.

Stalemate (July 1951 – July 1953)

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American M46 Patton tanks, painted with tiger heads thought to demoralize Chinese forces

ROK soldiers dump spent artillery casings

New Zealand artillery crew in action, 1952

For the remainder of the Korean War the UN Command and the PVA fought, but exchanged little territory; the stalemate held. Large-scale bombing of North Korea continued, and protracted armistice negotiations began 10 July 1951 at Kaesong. On the Chinese side, Zhou Enlai directed peace talks, and Li Kenong and Qiao Guanghua headed the negotiation team. Combat continued while the belligerents negotiated; the UN Command forces' goal was to recapture all of South Korea and to avoid losing territory. The PVA and the KPA attempted similar operations, and later effected military and psychological operations in order to test the UN Command's resolve to continue the war.

The principal battles of the stalemate include the Battle of Bloody Ridge (18 August–15 September 1951), the Battle of the Punchbowl (31 August-21 September 1951), the Battle of Heartbreak Ridge (13 September–15 October 1951), the Battle of Old Baldy (26 June–4 August 1952), the Battle of White Horse (6–15 October 1952), the Battle of Triangle Hill (14 October–25 November 1952), the Battle of Hill Eerie (21 March–21 June 1952), the sieges of Outpost Harry (10–18 June 1953), the Battle of the Hook (28–29 May 1953), the Battle of Pork Chop Hill (23 March–16 July 1953), and the Battle of Kumsong (13–27 July 1953).

Chinese troops suffered from deficient military equipment, serious logistical problems, overextended communication and supply lines, and the constant threat of UN bombers. All of these factors generally led to a rate of Chinese casualties that was far greater than the casualties suffered by UN troops. The situation became so serious that, on November 1951, Zhou Enlai called a conference in Shenyang to discuss the PVA's logistical problems. At the meeting it was decided to accelerate the construction of railways and airfields in the area, to increase the number of trucks available to the army, and to improve air defense by any means possible. These commitments did little to directly address the problems confronting PVA troops.

In the months after the Shenyang conference Peng Dehuai went to Beijing several times to brief Mao and Zhou about the heavy casualties suffered by Chinese troops and the increasing difficulty of keeping the front lines supplied with basic necessities. Peng was convinced that the war would be protracted, and that neither side would be able to achieve victory in the near future. On 24 February 1952, the Military Commission, presided over by Zhou, discussed the PVA's logistical problems with members of various government agencies involved in the war effort. After the government representatives emphasized their inability to meet the demands of the war, Peng, in an angry outburst, shouted: "You have this and that problem... You should go to the front and see with your own eyes what food and clothing the soldiers have! Not to speak of the casualties! For what are they giving their lives? We have no aircraft. We have only a few guns. Transports are not protected. More and more soldiers are dying of starvation. Can't you overcome some of your difficulties?" The atmosphere became so tense that Zhou was forced to adjourn the conference. Zhou subsequently called a series of meetings, where it was agreed that the PVA would be divided into three groups, to be dispatched to Korea in shifts; to accelerate the training of Chinese pilots; to provide more anti-aircraft guns to the front lines; to purchase more military equipment and ammunition from the Soviet Union; to provide the army with more food and clothing; and, to transfer the responsibility of logistics to the central government.

Armistice (July 1953 – November 1954)

Men from the Royal Australian Regiment, June 1953.

The on-again, off-again armistice negotiations continued for two years, first at Kaesong, on the border between North and South Korea, and then at the neighboring village of Panmunjom. A major, problematic negotiation point was prisoner of war (POW) repatriation. The PVA, KPA, and UN Command could not agree on a system of repatriation because many PVA and KPA soldiers refused to be repatriated back to the north, which was unacceptable to the Chinese and North Koreans. In the final armistice agreement, signed on 27 July 1953, a Neutral Nations Repatriation Commission, under the chairman Indian General K. S. Thimayya, was set up to handle the matter.

In 1952, the United States elected a new president, and on 29 November 1952, the president-elect, Dwight D. Eisenhower, went to Korea to learn what might end the Korean War. With the United Nations' acceptance of India's proposed Korean War armistice, the KPA, the PVA, and the UN Command ceased fire with the battle line approximately at the 38th parallel. Upon agreeing to the armistice, the belligerents established the Korean Demilitarized Zone (DMZ), which has since been patrolled by the KPA and ROKA, United States, and Joint UN Commands.

The Demilitarized Zone runs northeast of the 38th parallel; to the south, it travels west. The old Korean capital city of Kaesong, site of the armistice negotiations, originally was in pre-war South Korea, but now is part of North Korea. The United Nations Command, supported by the United States, the North Korean People's Army, and the Chinese People's Volunteers, signed the Armistice Agreement on 27 July 1953 to end the fighting. The Armistice also called upon the governments of South Korea, North Korea, China and the United States to participate in continued peace talks. The war is considered to have ended at this point, even though there was no peace treaty. North Korea nevertheless claims that it won the Korean War.

After the war, Operation Glory was conducted from July to November 1954, to allow combatant countries to exchange their dead. The remains of 4,167 U.S. Army and U.S. Marine Corps dead were exchanged for 13,528 KPA and PVA dead, and 546 civilians dead in UN prisoner-of-war camps were delivered to the South Korean government. After Operation Glory, 416 Korean War unknown soldiers were buried in the National Memorial Cemetery of the Pacific (The Punchbowl), on the island of Oahu, Hawaii. Defense Prisoner of War/Missing Personnel Office (DPMO) records indicate that the PRC and the DPRK transmitted 1,394 names, of which 858 were correct. From 4,167 containers of returned remains, forensic examination identified 4,219 individuals. Of these, 2,944 were identified as American, and all but 416 were identified by name. From 1996 to 2006, the DPRK recovered 220 remains near the Sino-Korean border.

Division of Korea (1954–present)

See also: Korean Demilitarized Zone

Delegates sign the Korean Armistice Agreement in P'anmunjŏm

The Korean Armistice Agreement provided for monitoring by an international commission. Since 1953, the Neutral Nations Supervisory Commission (NNSC), composed of members from the Swiss and Swedish Armed Forces, has been stationed near the DMZ.

In April 1975, South Vietnam's capital was captured by the North Vietnamese army. Encouraged by the success of Communist revolution in Indochina, Kim Il-sung saw it as an opportunity to invade the South. Kim visited China in April of that year, and met with Mao Zedong and Zhou Enlai to ask for military aid. Despite Pyongyang's expectations, however, Beijing refused to help North Korea for another war in Korea.

A U.S. Army officer confers with South Korean soldiers at Observation Post (OP) Ouellette, viewing northward, in April 2008.

The DMZ as seen from the north, 2005.

Since the armistice, there have been numerous incursions and acts of aggression by North Korea. In 1976, the axe murder incident was widely publicized. Since 1974, four incursion tunnels leading to Seoul have been uncovered. In 2010, a North Korean submarine torpedoed and sank the South Korean corvette ROKS Cheonan, resulting in the deaths of 46 sailors. Again in 2010, North Korea fired artillery shells on Yeonpyeong island, killing two military personnel and two civilians.

After a new wave of UN sanctions, on 11 March 2013, North Korea claimed that it invalidated the 1953 armistice. On 13 March 2013, North Korea confirmed it ended the 1953 Armistice and declared North Korea "is not restrained by the North-South declaration on non-aggression". On 30 March 2013, North Korea stated that it entered a "state of war" with South Korea and declared that "The long-standing situation of the Korean peninsula being neither at peace nor at war is finally over". Speaking on 4 April 2013, the U.S. Secretary of Defense, Chuck Hagel, informed the press that Pyongyang "formally informed" the Pentagon that it "ratified" the potential use of a nuclear weapon against South Korea, Japan and the United States of America, including Guam and Hawaii. Hagel also stated the United States would deploy the Terminal High Altitude Area Defense anti-ballistic missile system to Guam, because of a credible and realistic nuclear threat from North Korea.

In 2016, it was revealed that North Korea approached the United States about conducting formal peace talks to formally end the war. While the White House agreed to secret peace talks, the plan was rejected due to the country's refusal to discuss nuclear disarmament as part of the terms of the treaty. Any possibility of talks ended on 6 January when they conducted their fourth nuclear test.

Characteristics

Korean War memorials are found in every UN Command Korean War participant country; this one is in Pretoria, South Africa.

Casualties

According to the data from the U.S. Department of Defense, the United States suffered 33,686 battle deaths, along with 2,830 non-battle deaths, during the Korean War. U.S. battle deaths were 8,516 up to their first engagement with the Chinese on 1 November 1950. South Korea reported some 373,599 civilian and 137,899 military deaths. Western sources estimate the PVA suffered about 400,000 killed and 486,000 wounded, while the KPA suffered 215,000 killed and 303,000 wounded.

Data from official Chinese sources, on the other hand, reported that the PVA had suffered 114,000 battle deaths, 34,000 non-battle deaths, 340,000 wounded, 7,600 missing and during the war. 7,110 Chinese POWs were repatriated to China. Chinese sources also reported that North Korea had suffered 290,000 casualties, 90,000 captured and a large number of civilian deaths.

The Chinese and North Koreans estimated that about 390,000 soldiers from the United States, 660,000 soldiers from South Korea and 29,000 other UN soldiers were "eliminated" from the battlefield.

Recent scholarship puts the full battle death toll on all sides at just over 1.2 million.

Armored warfare

The initial assault by North Korean KPA forces was aided by the use of Soviet T-34-85 tanks. A North Korean tank corps equipped with about 120 T-34s spearheaded the invasion. These drove against a ROK Army with few anti-tank weapons adequate to deal with the Soviet T-34s. Additional Soviet armor was added as the offensive progressed. The North Korean tanks had a good deal of early successes against South Korean infantry, elements of the 24th Infantry Division, and the United States built M24 Chaffee light tanks that they encountered. Interdiction by ground attack aircraft was the only means of slowing the advancing Korean armor. The tide turned in favour of the United Nations forces in August 1950 when the North Koreans suffered major tank losses during a series of battles in which the UN forces brought heavier equipment to bear, including M4A3 Sherman medium tanks backed by U.S. M26 heavy tanks, along with British Centurion, Churchill, and Cromwell tanks.

The U.S. landings at Inchon on 15 September cut off the North Korean supply lines, causing their armored forces and infantry to run out of fuel, ammunition, and other supplies. As a result, the North Koreans had to retreat, and many of the T-34s and heavy weapons had to be abandoned. By the time the North Koreans withdrew from the South, a total of 239 T-34s and 74 SU-76s were lost. After November 1950, North Korean armor was rarely encountered.

Following the initial assault by the north, the Korean War saw limited use of tanks and featured no large-scale tank battles. The mountainous, forested terrain, especially in the Eastern Central Zone, was poor tank country, limiting their mobility. Through the last two years of the war in Korea, UN tanks served largely as infantry support and mobile artillery pieces.

Naval warfare

To disrupt North Korean communications, USS Missouri fires a salvo from its 16-inch guns at shore targets near Chongjin, North Korea, 21 October 1950

Further information: List of U.S. Navy ships sunk or damaged in action during the Korean conflict

Because neither Korea had a significant navy, the Korean War featured few naval battles. A skirmish between North Korea and the UN Command occurred on 2 July 1950; the U.S. Navy cruiser USS Juneau, the Royal Navy cruiser HMS Jamaica, and the frigate HMS Black Swan fought four North Korean torpedo boats and two mortar gunboats, and sank them. USS Juneau later sank several ammunition ships that had been present. The last sea battle of the Korean War occurred at Inchon, days before the Battle of Incheon; the ROK ship PC-703 sank a North Korean mine layer in the Battle of Haeju Island, near Inchon. Three other supply ships were sunk by PC-703 two days later in the Yellow Sea. Thereafter, vessels from the UN nations held undisputed control of the sea about Korea. The gun ships were used in shore bombardment, while the aircraft carriers provided air support to the ground forces.

During most of the war, the UN navies patrolled the west and east coasts of North Korea, sinking supply and ammunition ships and denying the North Koreans the ability to resupply from the sea. Aside from very occasional gunfire from North Korean shore batteries, the main threat to United States and UN navy ships was from magnetic mines. During the war, five U.S. Navy ships were lost to mines: two minesweepers, two minesweeper escorts, and one ocean tug. Mines and gunfire from North Korean coastal artillery damaged another 87 U.S. warships, resulting in slight to moderate damage.

Aerial warfare

Further information: MiG Alley, USAF Units and Aircraft of the Korean War, and Korean People's Air Force

The Korean War was the first war in which jet aircraft played the central role in air combat. Once-formidable fighters such as the P-51 Mustang, F4U Corsair, and Hawker Sea Fury—all piston-engined, propeller-driven, and designed during World War II—relinquished their air-superiority roles to a new generation of faster, jet-powered fighters arriving in the theater. For the initial months of the war, the P-80 Shooting Star, F9F Panther, Gloster Meteor and other jets under the UN flag dominated North Korea's prop-driven air force of Soviet Yakovlev Yak-9 and Lavochkin La-9s.

The Chinese intervention in late October 1950 bolstered the Korean People's Air Force (KPAF) of North Korea with the MiG-15, one of the world's most advanced jet fighters. The heavily armed MiGs were faster than first-generation UN jets and so could reach and destroy U.S. B-29 Superfortress bomber flights despite their fighter escorts. With increasing B-29 losses, the Air Force was forced to switch from a daylight bombing campaign to a safer but less accurate nighttime bombing of targets.

A B-29 Superfortress bomber dropping its bombs.

The USAF countered the MiG-15 by sending over three squadrons of its most capable fighter, the F-86 Sabre. These arrived in December 1950. The MiG was designed as a bomber interceptor. It had a very high service ceiling— and carried very heavy weaponry: one 37 mm cannon and two 23 mm cannons. The F-86 had a ceiling of and were armed with six .50 caliber (12.7 mm) machine guns, which were range adjusted by radar gunsights. If coming in at higher altitude the advantage of engaging or not went to the MiG. Once in a level flight dogfight, both swept-wing designs attained comparable maximum speeds of around . The MiG climbed faster, but the Sabre turned and dived better.

In summer and autumn 1951, the outnumbered Sabres of the USAF's 4th Fighter Interceptor Wing—only 44 at one point—continued seeking battle in MiG Alley, where the Yalu River marks the Chinese border, against Chinese and North Korean air forces capable of deploying some 500 aircraft. Following Colonel Harrison Thyng's communication with the Pentagon, the 51st Fighter-Interceptor Wing finally reinforced the beleaguered 4th Wing in December 1951; for the next year-and-a-half stretch of the war, aerial warfare continued.

A US Navy Sikorsky HO4S flying near USS Sicily

Unlike the Vietnam War, in which the Soviet Union only officially sent "advisers", in the Korean aerial war Soviet forces participated via the 64th Airborne Corps. Fearful of confronting the United States directly, the Soviet Union denied involvement of their personnel in anything other than an advisory role, but air combat quickly resulted in Soviet pilots dropping their code signals and speaking over the wireless in Russian. This known direct Soviet participation was a casus belli that the UN Command deliberately overlooked, lest the war for the Korean peninsula expand to include the Soviet Union, and potentially escalate into atomic warfare. 1,106 enemy airplanes were officially downed by the Soviet pilots, 52 of whom got ace status. The Soviet system of confirming air kills erred on the conservative side; the pilot's words had to be corroborated and enemy aircraft falling into the sea were not counted, the number might exceed 1,106.

After the war, and to the present day, the USAF reports an F-86 Sabre kill ratio in excess of 10:1, with 792 MiG-15s and 108 other aircraft shot down by Sabres, and 78 Sabres lost to enemy fire. The Soviet Air Force reported some 1,100 air-to-air victories and 335 MiG combat losses, while China's People's Liberation Army Air Force (PLAAF) reported 231 combat losses, mostly MiG-15s, and 168 other aircraft lost. The KPAF reported no data, but the UN Command estimates some 200 KPAF aircraft lost in the war's first stage, and 70 additional aircraft after the Chinese intervention. The USAF disputes Soviet and Chinese claims of 650 and 211 downed F-86s, respectively. However, one unconfirmed source claims that the U.S. Air Force has more recently cited 230 losses out of 674 F-86s deployed to Korea.

The Korean War marked a major milestone not only for fixed-wing aircraft, but also for rotorcraft, featuring the first large-scale deployment of helicopters for medical evacuation (medevac). In 1944–1945, during the Second World War, the YR-4 helicopter saw limited ambulance duty, but in Korea, where rough terrain trumped the jeep as a speedy medevac vehicle, helicopters like the Sikorsky H-19 helped reduce fatal casualties to a dramatic degree when combined with complementary medical innovations such as Mobile Army Surgical Hospitals. The limitations of jet aircraft for close air support highlighted the helicopter's potential in the role, leading to development of the AH-1 Cobra and other helicopter gunships used in the Vietnam War (1965–75).

Bombing of North Korea

The first major U.S. strategic bombing campaign against North Korea, begun in late July 1950, was conceived as similar he major offensives of World War II. On 12 August 1950, the U.S. Air Force dropped 625 tons of bombs on North Korea; two weeks later, the daily tonnage increased to some 800 tons. Following the intervention of the Chinese in November, General MacArthur ordered increased bombing campaign on North Korea which included incendiary attacks against their arsenals and communications centers and especially against the "Korean end" of all the bridges across the Yalu River. As with the aerial bombing campaigns over Germany and Japan in World War II, the nominal objective of the U.S. Air Force was to destroy North Korea's war infrastructure and shatter their morale After MacArthur was removed as Supreme Commander in Korea in April 1951, his successors continued this policy and ultimately extended it to all of North Korea. The U.S. a total of dropped 635,000 tons of bombs, including 32,557 tons of napalm, on Korea, more than during the whole Pacific campaign of World War II.

A USAF Douglas B-26B Invader of the 452nd Bombardment Wing bombing a target in North Korea, 29 May 1951.

Almost every substantial building in North Korea was destroyed as a result. The war's highest-ranking American POW, U.S. Major General William F. Dean, reported that the majority of North Korean cities and villages he saw were either rubble or snow-covered wasteland. North Korean factories, schools, hospitals, and government offices were forced to move underground, and air defenses were "non-existent." In November 1950, the North Korean leadership instructed their population to build dugouts and mud huts and to dig underground tunnels, in order to solve the acute housing problem. U.S. Air Force General Curtis LeMay commented, "we went over there and fought the war and eventually burned down every town in North Korea anyway, some way or another, and some in South Korea, too." Pyongyang, which saw 75 percent of its area destroyed, was so devastated that bombing was halted as there were no longer any worthy targets. On 28 November, Bomber Command reported on the campaign's progress: 95 percent of Manpojin was destroyed, along with 90 percent of Hoeryong, Namsi and Koindong, 85 percent of Chosan, 75 percent of both Sakchu and Huichon, and 20 percent of Uiju. According to USAF damage assessments, "eighteen of twenty-two major cities in North Korea had been at least half obliterated." By the end of the campaign, US bombers had difficulty in finding targets and were reduced to bombing footbridges or jettisoning their bombs into the sea.

As well as conventional bombing, the Communist side claimed that the U.S. used biological weapons. These claims have been disputed; Conrad Crane asserts that while the U.S. worked towards developing chemical and biological weapons, the American military "possessed neither the ability, nor the will", to use them in combat.

U.S. threat of atomic warfare

Mark 4 bomb, seen on display, transferred to the 9th Bombardment Wing, Heavy

On 5 November 1950, the Joint Chiefs of Staff (JCS) issued orders for the retaliatory atomic bombing of Manchurian PRC military bases, if either their armies crossed into Korea or if PRC or KPA bombers attacked Korea from there. The President ordered the transfer of nine Mark 4 nuclear bombs "to the Air Force's Ninth Bomb Group, the designated carrier of the weapons ... [and] signed an order to use them against Chinese and Korean targets", which he never transmitted.

Many American officials viewed the deployment of nuclear-capable (but not nuclear-armed) B-29 bombers to Britain as helping to resolve the Berlin Blockade of 1948–1949. Truman and Eisenhower both had military experience and viewed nuclear weapons as potentially usable components of their military. During Truman's first meeting to discuss the war on 25 June 1950, he ordered plans be prepared for attacking Soviet forces if they entered the war. By July, Truman approved another B-29 deployment to Britain, this time with bombs (but without their cores), to remind the Soviets of American offensive ability. Deployment of a similar fleet to Guam was leaked to The New York Times. As United Nations forces retreated to Pusan, and the CIA reported that mainland China was building up forces for a possible invasion of Taiwan, the Pentagon believed that Congress and the public would demand using nuclear weapons if the situation in Korea required them.

As Chinese forces pushed back the United States forces from the Yalu River, Truman stated during a 30 November 1950 press conference that using nuclear weapons was "always [under] active consideration", with control under the local military commander. The Indian ambassador, K. Madhava Panikkar, reports "that Truman announced he was thinking of using the atom bomb in Korea. But the Chinese seemed unmoved by this threat ... The propaganda against American aggression was stepped up. The 'Aid Korea to resist America' campaign was made the slogan for increased production, greater national integration, and more rigid control over anti-national activities. One could not help feeling that Truman's threat came in useful to the leaders of the Revolution, to enable them to keep up the tempo of their activities."

After his statement caused concern in Europe, Truman met on 4 December 1950 with UK prime minister and Commonwealth spokesman Clement Attlee, French Premier René Pleven, and Foreign Minister Robert Schuman to discuss their worries about atomic warfare and its likely continental expansion. The United States' forgoing atomic warfare was not because of "a disinclination by the Soviet Union and People's Republic of China to escalate" the Korean War, but because UN allies—notably from the UK, the Commonwealth, and France—were concerned about a geopolitical imbalance rendering NATO defenseless while the United States fought China, who then might persuade the Soviet Union to conquer Western Europe. The Joint Chiefs of Staff advised Truman to tell Attlee that the United States would use nuclear weapons only if necessary to protect an evacuation of UN troops, or to prevent a "major military disaster".

On 6 December 1950, after the Chinese intervention repelled the UN Command armies from northern North Korea, General J. Lawton Collins (Army Chief of Staff), General MacArthur, Admiral C. Turner Joy, General George E. Stratemeyer, and staff officers Major General Doyle Hickey, Major General Charles A. Willoughby, and Major General Edwin K. Wright met in Tokyo to plan strategy countering the Chinese intervention; they considered three potential atomic warfare scenarios encompassing the next weeks and months of warfare.

• In the first scenario: If the PVA continued attacking in full and the UN Command was forbidden to blockade and bomb China, and without ROC reinforcements, and without an increase in U.S. forces until April 1951 (four National Guard divisions were due to arrive), then atomic bombs might be used in North Korea.
• In the second scenario: If the PVA continued full attacks and the UN Command blockaded China and had effective aerial reconnaissance and bombing of the Chinese interior, and the ROC soldiers were maximally exploited, and tactical atomic bombing was to hand, then the UN forces could hold positions deep in North Korea.
• In the third scenario: if China agreed to not cross the 38th parallel border, General MacArthur recommended UN acceptance of an armistice disallowing PVA and KPA troops south of the parallel, and requiring PVA and KPA guerrillas to withdraw northwards. The U.S. Eighth Army would remain to protect the Seoul–Incheon area, while X Corps would retreat to Pusan. A UN commission should supervise implementation of the armistice.

Both the Pentagon and the State Department were cautious about using nuclear weapons because of the risk of general war with China and the diplomatic ramifications. Truman and his senior advisors agreed, and never seriously considered using them in early December 1950 despite the poor military situation in Korea.

In 1951, the U.S. escalated closest to atomic warfare in Korea. Because China deployed new armies to the Sino-Korean frontier, pit crews at the Kadena Air Base, Okinawa, assembled atomic bombs for Korean warfare, "lacking only the essential pit nuclear cores". In October 1951, the United States effected Operation Hudson Harbor to establish a nuclear weapons capability. USAF B-29 bombers practised individual bombing runs from Okinawa to North Korea (using dummy nuclear or conventional bombs), coordinated from Yokota Air Base in east-central Japan. Hudson Harbor tested "actual functioning of all activities which would be involved in an atomic strike, including weapons assembly and testing, leading, ground control of bomb aiming". The bombing run data indicated that atomic bombs would be tactically ineffective against massed infantry, because the "timely identification of large masses of enemy troops was extremely rare."

Ridgway was authorized to use nuclear weapons if a major air attack originated from outside Korea. An envoy was sent to Hong Kong to deliver a warning to China. The message likely caused Chinese leaders to be more cautious about potential American use of nuclear weapons, but whether they learned about the B-29 deployment is unclear and the failure of the two major Chinese offensives that month likely was what caused them to shift to a defensive strategy in Korea. The B-29s returned to the United States in June.

Despite the greater destructive power deploying atomic weapons would bring to the war, their effects on determining the war's outcome would have likely been minimal. Tactically, given the dispersed nature of Chinese and North Korean forces, the relatively primitive infrastructure for staging and logistics centers, and the small number of bombs available (most would have been conserved for use against the Soviets), atomic attacks would have limited effects against the ability of China to mobilize and move forces. Strategically, attacking Chinese cities to destroy civilian industry and infrastructure would cause the immediate dispersion of the leadership away from such areas and give propaganda value for the communists to galvanize the support of Chinese civilians. Since the Soviets were not expected to intervene with their few primitive atomic weapons on China or North Korea's behalf if the U.S. used theirs first, factors such as little operational value and the lowering of the "threshold" for using atomic weapons against non-nuclear states in future conflicts played more of a role in not employing them than the threat of a possible nuclear exchange.

When Eisenhower succeeded Truman in early 1953 he was similarly cautious about using nuclear weapons in Korea, including for diplomatic purposes to encourage progress in ongoing truce discussions. The administration prepared contingency plans to use them against China, but like Truman, the new president feared doing so would result in Soviet attacks on Japan. The war ended as it began, without American nuclear weapons deployed near battle.

War crimes

Civilian deaths and massacres

Further information: Bodo League massacre, Seoul National University Hospital massacre, No Gun Ri Massacre, Sinchon Massacre, Ganghwa massacre, Sancheong-Hamyang massacre, and Geochang massacre

South Korean soldiers walk among the bodies of political prisoners executed near Daejon, July 1950

Civilians killed during a night battle near Yongsan, August 1950

There were numerous atrocities and massacres of civilians throughout the Korean war committed by both the North and South Koreans. Many started on the first days of the war. South Korean President Syngman Rhee ordered the Bodo League massacre on 28 June, beginning numerous killings of more than 100,000 suspected leftist sympathizers and their families by South Korean officials and right-wing groups. During the massacre, the British protested to their allies and saved some citizens.

In occupied areas, North Korean Army political officers purged South Korean society of its intelligentsia by executing every educated person—academic, governmental, religious—who might lead resistance against the North; the purges continued during the NPA retreat. When the North Koreans retreated north in September 1950, they abducted tens of thousands of South Korean men. The reasons are not clear, but the intention might have been to acquire skilled professionals to the North.

In addition to conventional military operations, North Korean soldiers fought the UN forces by infiltrating guerrillas among refugees. These soldiers disguised as refugees would approach UN forces asking for food and help, then open fire and attack. U.S. troops acted under a "shoot-first-ask-questions-later" policy against any civilian refugee approaching U.S. battlefield positions, a policy that led U.S. soldiers to kill an estimated 400 civilians at No Gun Ri (26–29 July 1950) in central Korea because they believed some of the refugees to be North Korean soldiers in disguise. The South Korean Truth and Reconciliation Commission defended this policy as a "military necessity".

Beginning in 2005, the South Korean Truth and Reconciliation Commission has investigated numerous atrocities committed by the Japanese colonial government, North Korean military, U.S. military, and the authoritarian South Korean government. It has investigated atrocities before, during and after the Korean War.

The Commission verified over 14,000 civilians were killed in the Jeju uprising (1948–49) that involved South Korean military and paramilitary units against pro-North Korean guerrillas. Although most of the fighting subsided by 1949, it continued until 1950. The Commission estimates 86% of the civilians were killed by South Korean forces. The Americans on the island documented the events, but never intervened.

Prisoners of war

See also: Korean POWs detained in North Korea, Hill 303 massacre, and List of American and British defectors in the Korean War

A U.S. Marine guards North Korean prisoners of war aboard an American warship in 1951.

During the first days of the war North Korean soldiers committed the Seoul National University Hospital massacre.

The United States reported that North Korea mistreated prisoners of war: soldiers were beaten, starved, put to forced labor, marched to death, and summarily executed.

The KPA killed POWs at the battles for Hill 312, Hill 303, the Pusan Perimeter, and Daejeon; these massacres were discovered afterwards by the UN forces. Later, a U.S. Congress war crimes investigation, the United States Senate Subcommittee on Korean War Atrocities of the Permanent Subcommittee of the Investigations of the Committee on Government Operations, reported that "two-thirds of all American prisoners of war in Korea died as a result of war crimes".

Although the Chinese rarely executed prisoners like their North Korean counterparts, mass starvation and diseases swept through the Chinese-run POW camps during the winter of 1950–51. About 43 percent of U.S. POWs died during this period. The Chinese defended their actions by stating that all Chinese soldiers during this period were suffering mass starvation and diseases due to logistical difficulties. The UN POWs said that most of the Chinese camps were located near the easily supplied Sino-Korean border, and that the Chinese withheld food to force the prisoners to accept the communism indoctrination programs. According to Chinese reports, over a thousand U.S. POWs died by the end of June 1951, while a dozen British POWs died, and all Turkish POW survived. According to Hastings, wounded U.S. POWs died for lack of medical attention and were fed a diet of corn and millet "devoid of vegetables, almost barren of proteins, minerals, or vitamins" with only 1/3 the calories of their usual diet. Especially in early 1951, thousands of prisoners lost the will to live and "declined to eat the mess of sorghum and rice they were provided."

Two Hill 303 survivors after being rescued by American units, 17 August 1950.

Chinese POWs said that the UN forces helped anti-Communism POWs to torture Chinese POWs, such as to put anti-Communism tattoos on their body by force, so that they would have to refuse to be repatriated back to the north. They even killed Communist POWs in public, to frighten the others.

The unpreparedness of U.S. POWs to resist heavy communist indoctrination during the Korean War led to the Code of the United States Fighting Force which governs how U.S. military personnel in combat should act when they must "evade capture, resist while a prisoner or escape from the enemy".

North Korea may have detained up to 50,000 South Korean POWs after the ceasefire. Over 88,000 South Korean soldiers were missing and the Communists' claimed they captured 70,000 South Koreans. However, when ceasefire negotiations began in 1951, the Communists reported they held only 8,000 South Koreans. The UN Command protested the discrepancies and alleged that the Communists were forcing South Korean POWs to join the KPA.

The Communist side denied such allegations. They claimed their POW rosters were small because many POWs were killed in UN air raids and that they had released ROK soldiers at the front. They insisted only volunteers were allowed to serve in the KPA. By early 1952, UN negotiators gave up trying to get back the missing South Koreans. The POW exchange proceeded without access to South Korean POWs not on the Communist rosters.

North Korea continued to claim that any South Korean POW who stayed in the North did so voluntarily. However, since 1994, South Korean POWs have been escaping North Korea on their own after decades of captivity. As of 2010, the South Korean Ministry of Unification reported that 79 ROK POWs escaped the North. The South Korean government estimates 500 South Korean POWs continue to be detained in North Korea.

The escaped POWs have testified about their treatment and written memoirs about their lives in North Korea. They report they were not told about the POW exchange procedures, and were assigned to work in mines in the remote northeastern regions near the Chinese and Russian border. Declassified Soviet Foreign Ministry documents corroborate such testimony.

In 1997, the Geoje POW Camp in South Korea was turned into a memorial.

Starvation

See also: National Defense Corps Incident

In December 1950, National Defense Corps was founded; the soldiers were 406,000 drafted citizens. In the winter of 1951, 50,000 to 90,000 South Korean National Defense Corps soldiers starved to death while marching southward under the Chinese offensive when their commanding officers embezzled funds earmarked for their food. This event is called the National Defense Corps Incident. There is no evidence that Syngman Rhee was personally involved in or benefited from the corruption.

Recreation

Further information: United Service Organizations

Bob Hope entertained X Corps in Korea on 26 October 1950.

In 1950, Secretary of Defense George C. Marshall and Secretary of the Navy Francis P. Matthews called on the USO which was disbanded by 1947 to provide support for U.S. servicemen. By the end of the war, more than 113,000 American USO volunteers were working at home front and abroad. Many stars came to Korea to give their performances. Throughout the Korean War, UN Comfort Stations were operated by South Korean officials for UN soldiers.

Aftermath

Main article: Aftermath of the Korean War

File:Korean Peninsula at night - 2012 - NASA.png

The Korean Peninsula at night, shown in a 2012 composite photograph from NASA.

Postwar recovery was different in the two Koreas. South Korea stagnated in the first postwar decade. In 1953, South Korea and the United States concluded a Mutual Defense Treaty. In 1960, the April Revolution occurred and students joined an anti-Syngman Rhee demonstration; 142 were killed by police; in consequence Syngman Rhee resigned and left for exile in the United States. Park Chung-hee's May 16 coup enabled social stability. In the 1960s, prostitution and related services earned 25 percent of South Korean GNP. From 1965 to 1973, South Korea dispatched troops to Vietnam and received $235,560,000 allowance and military procurement from the United States. GNP increased fivefold during the Vietnam War. South Korea industrialized and modernized. Contemporary North Korea remains underdeveloped. South Korea had one of the world's fastest-growing economies from the early 1960s to the late 1990s. In 1957 South Korea had a lower per capita GDP than Ghana, and by 2010 it was ranked thirteenth in the world (Ghana was 86th).

Following extensive USAF bombing, North Korea "had been virtually destroyed as an industrial society." After the armistice, Kim Il-Sung requested Soviet economic and industrial assistance. In September 1953, the Soviet government agreed to "cancel or postpone repayment for all ... outstanding debts", and promised to grant North Korea one billion rubles in monetary aid, industrial equipment and consumer goods. Eastern European members of the Soviet Bloc also contributed with "logistical support, technical aid, [and] medical supplies." China canceled North Korea's war debts, provided 800 million yuan, promised trade cooperation, and sent in thousands of troops to rebuild damaged infrastructure.

Postwar, about 100,000 North Koreans were executed in purges. According to Rummel, forced labor and concentration camps were responsible for over one million deaths in North Korea from 1945 to 1987; others have estimated 400,000 deaths in concentration camps alone. Estimates based on the most recent North Korean census suggest that 240,000 to 420,000 people died as a result of the 1990s North Korean famine and that there were 600,000 to 850,000 unnatural deaths in North Korea from 1993 to 2008. The North Korean government has been accused of "crimes against humanity" for its alleged culpability in creating and prolonging the 1990s famine. A study by South Korean anthropologists of North Korean children who had defected to China found that 18-year-old males were 5 inches shorter than South Koreans their age because of malnutrition.

South Korean anti-Americanism after the war was fueled by the presence and behavior of American military personnel (USFK) and U.S. support for the authoritarian regime, a fact still evident during the country's democratic transition in the 1980s. However, anti-Americanism has declined significantly in South Korea in recent years, from 46% favorable in 2003 to 74% favorable in 2011, making South Korea one of the most pro-American countries in the world.

In addition, a large number of mixed-race "G.I. babies" (offspring of American and other UN soldiers and Korean women) were filling up the country's orphanages. Because Korean traditional society places significant weight on paternal family ties, bloodlines, and purity of race, children of mixed race or those without fathers are not easily accepted in South Korean society. International adoption of Korean children began in 1954. The U.S. Immigration Act of 1952 legalized the naturalization of non-whites as American citizens, and made possible the entry of military spouses and children from South Korea after the Korean War. With the passage of the Immigration Act of 1965, which substantially changed U.S. immigration policy toward non-Europeans, Koreans became one of the fastest-growing Asian groups in the United States.

Mao Zedong's decision to take on the United States in the Korean War was a direct attempt to confront what the Communist bloc viewed as the strongest anti-Communist power in the world, undertaken at a time when the Chinese Communist regime was still consolidating its own power after winning the Chinese Civil War. Mao supported intervention not to save North Korea, but because he believed that a military conflict with the United States was inevitable after the United States entered the Korean War, and to appease the Soviet Union to secure military dispensation and achieve Mao's goal of making China a major world military power. Mao was equally ambitious in improving his own prestige inside the communist international community by demonstrating that his Marxist concerns were international. In his later years Mao believed that Stalin only gained a positive opinion of him after China's entrance into the Korean War. Inside Mainland China, the war improved the long-term prestige of Mao, Zhou, and Peng, allowing the Chinese Communist Party to increase its legitimacy while weakening anti-Communist dissent.

North Koreans touring the Museum of American War Atrocities in 2009

The Chinese government have encouraged the point of view that the war was initiated by the United States and South Korea, though ComIntern documents have shown that Mao sought approval from Joseph Stalin to enter the war. In Chinese media, the Chinese war effort is considered as an example of China's engaging the strongest power in the world with an under-equipped army, forcing it to retreat, and fighting it to a military stalemate. These successes were contrasted with China's historical humiliations by Japan and by Western powers over the previous hundred years, highlighting the abilities of the People's Liberation Army and the Chinese Communist Party. The most significant negative long-term consequence of the war (for China) was that it led the United States to guarantee the safety of Chiang Kai-shek's regime in Taiwan, effectively ensuring that Taiwan would remain outside of PRC control until the present day. Mao had also discovered the usefulness of large-scale mass movements in the war while implementing them among most of his ruling measures over PRC. Finally, anti-American sentiments, which were already a significant factor during the Chinese Civil War, was ingrained into Chinese culture during the Communist propaganda campaigns of the Korean War.

The Korean War affected other participant combatants. Turkey, for example, entered NATO in 1952, and the foundation was laid for bilateral diplomatic and trade relations with South Korea.

See also

• 1st Commonwealth Division
• Australia in the Korean War
• Canada in the Korean War
• Historical revisionism (negationism)#North Korea and the Korean War
• Joint Advisory Commission, Korea
• Korean conflict
• Korean DMZ Conflict (1966–1969)
• Korean reunification
• Korean War in popular culture
• List of books about the Korean War
• List of Korean War weapons
• List of Korean War Medal of Honor recipients
• List of military equipment used in the Korean War
• List of wars and anthropogenic disasters by death toll
• New Zealand in the Korean War
• Operation Big Switch
• Operation Little Switch
• Operation Moolah

• Partisans in Korean War, Partisan Movement
• Philippine Expeditionary Forces to Korea
• Pyongyang Sally
• UNCMAC — the UN Command Military Armistice Commission operating from 1953 to the present
• UNCURK — the 1951 UN Commission for the Unification and Rehabilitation of Korea
• UNTCOK — the 1950 United Nations Temporary Commission on Korea
• M*A*S*H – TV series
• MASH – film
• War memorials:
  • United Nations Memorial Cemetery, Busan, Republic of Korea
  • Korean War Veterans Memorial, Washington, D.C.
  • Philadelphia Korean War Memorial
  • National War Memorial (New Zealand)
  • Korean War Memorial Wall, Brampton, Ontario
  • War Memorial of Korea Yongsan-dong, Yongsan-gu, Seoul, South Korea

References

• Zaloga, Steven J., Jim Kinnear, Andrey Aksenov & Aleksandr Koshchavtsev (1997). Soviet Tanks in Combat 1941–45: The T-28, T-34, T-34-85, and T-44 Medium Tanks, Hong Kong: Concord Publication. ISBN 962-361-615-5

External links

Historical

• Anniversary of the Korean War Armistice: Truman on Acheson's Crucial Role in Going to War Shapell Manuscript Foundation
• Korean War resources, Dwight D. Eisenhower Presidential Library
• North Korea International Documentation Project
• Grand Valley State University Veteran's History Project digital collection
• The Forgotten War, Remembered – four testimonials in The New York Times
• Collection of Books and Research Materials on the Korean War an online collection of the United States Army Center of Military History
• Korean War, US Army Signal Corps Photograph Collection US Army Heritage and Education Center, Carlisle, Pennsylvania
• The Korean War at History.com
• Korean-War.com
• Koreanwar-educator.org
• The short film Film No. 927 is available for free download at the Internet Archive.

Media

• The Korean War You Never Knew – slideshows by Life magazine
• QuickTime sequence of 27 maps adapted from the West Point Atlas of American Wars
• Animation for operations in 1950
• Animation for operations in 1951
• US Army Korea Media Center official Korean War online image archive
• Rare pictures of the Korean War from the U.S. Library of Congress and National Archives
• The Korean War in Color on YouTube
• Land of the Morning Calm Canadians in Korea – multimedia project including veteran interviews
• Pathé Online newsreel archive featuring films on the war
• CBC Digital Archives—Forgotten Heroes: Canada and the Korean War

Organizations

• Korea Defense Veterans of America
• Korean War Ex-POW Association
• Korean War Veterans Association
• The Center for the Study of the Korean War

Memorials

• Korean Children's War Memorial
• Chinese 50th Anniversary Korean War Memorial