The Korean War (25 June 1950 – armistice signed 27 July 1953) was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China (PRC), with military material aid from the Soviet Union. The war was a result of the physical division of Korea by an agreement of the victorious Allies at the conclusion of the Pacific War at the end of World War II. The Korean peninsula was ruled by Japan from 1910 until the end of World War II. Following the surrender of Japan in 1945, American administrators divided the peninsula along the 38th Parallel, with United States troops occupying the southern part and Soviet troops occupying the northern part.

The failure to hold free elections throughout the Korean Peninsula in 1948 deepened the division between the two sides, and the North established a Communist government. The 38th Parallel increasingly became a political border between the two Koreas. Although reunification negotiations continued in the months preceding the war, tension intensified. Cross-border skirmishes and raids at the 38th Parallel persisted. The situation escalated into open warfare when North Korean forces invaded South Korea on 25 June 1950. It was the first significant armed conflict of the Cold War.

The United Nations, particularly the United States, came to the aid of South Korea in repelling the invasion, but within two months the defenders were pushed back to the Pusan perimeter, a small area in the south of the country, before the North Koreans were stopped. A rapid UN counter-offensive then drove the North Koreans past the 38th Parallel and almost to the Yalu River, and the People's Republic of China (PRC) entered the war on the side of the North. The Chinese launched a counter-offensive that pushed the United Nations forces back across the 38th Parallel. The Soviet Union materially aided the North Korean and Chinese armies. In 1953, the war ceased with an armistice that restored the border between the Koreas near the 38th Parallel and created the Korean Demilitarized Zone (DMZ), a wide buffer zone between the two Koreas. Minor outbreaks of fighting continue to the present day.

With both North and South Korea sponsored by external powers, the Korean War was a proxy war. From a military science perspective, it combined strategies and tactics of World War I and World War II: it began with a mobile campaign of swift infantry attacks followed by air bombing raids, but became a static trench war by July 1951.

Background

Etymology

In South Korea the war is usually referred to as "625" or the 6–2–5 War (yug-i-o jeonjaeng), 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). Alternatively, it is called the Chosǒn chǒnjaeng ("Chosǒn war", Chosǒn being what North Koreans call Korea). In the People's Republic of China the war is called the War to Resist U.S. Aggression and Aid Korea (). The "Korean War" (朝鮮戰爭/朝鲜战争; pinyin: Cháoxiǎn zhànzhēng) is more commonly used today. ''Cháoxiǎn'' is the Chinese pronunciation of the Korean name "Chosǒn".

Japanese rule (1910–1945)

Korean nationalists and the intelligentsia fled the country, and some founded the Provisional Korean Government in 1919, which was headed by Syngman Rhee in Shanghai. This government-in-exile was recognized by few countries. From 1919 to 1925 and beyond, Korean communists led and were the primary agents of internal and external warfare against the Japanese.

Korea under Japanese rule 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. In 1938, the Colonial Government established labor conscription.

In China, the National Revolutionary Army and the Communist People's Liberation Army helped organize refugee Korean patriots and independence fighters 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, fought the Japanese in Korea and Manchuria.

During World War II, the Japanese used Korea's food, livestock, and metals for their war effort. Japanese forces in Korea increased from 46,000 soldiers in 1941 to 300,000 in 1945. Japanese Korea conscripted 2.6 million forced laborers controlled with a collaborationist Korean police force; some 723,000 people were sent to work in the overseas empire and in metropolitan Japan. By 1942, Korean men were being conscripted into the Imperial Japanese Army. By January 1945, Koreans comprised 32% of Japan's labor force. In August 1945, when the United States dropped atomic bombs on Hiroshima and Nagasaki, around 25% of those killed were Koreans. At the end of the war, other world powers did not recognize Japanese rule in Korea and Taiwan.

Meanwhile, at the Cairo Conference (November 1943), Nationalist China, the United Kingdom, and the United States decided "in due course Korea shall become free and independent". Later, the Yalta Conference (February 1945) granted to the Soviet Union European "buffer zones"—satellite states accountable to Moscow—as well as an expected Soviet pre-eminence in China and Manchuria, in return for joining the Allied Pacific War effort against Japan.

Soviet invasion of Manchuria (1945)

On 10 August 1945, with the 15 August Japanese surrender near, the Americans doubted whether the Soviets would honor their part of the Joint Commission, the US-sponsored Korean occupation agreement. A month earlier, Colonel Dean Rusk and Colonel Charles H. Bonesteel III divided the Korean peninsula at the 38th parallel after hurriedly deciding (in thirty minutes) that the US Korean Zone of Occupation had to have a minimum of two ports.

Explaining why the occupation zone demarcation was positioned at the 38th parallel, Rusk observed, "even though it was further north than could be realistically reached by US 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", especially when "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." The Soviets agreed to the US occupation zone demarcation to improve their negotiating position regarding the occupation zones in Eastern Europe, and because each would accept Japanese surrender where they stood.

Chinese Civil War (1945–1949)

After the end of Second Sino-Japanese War, 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 materiel and manpower. According to Chinese sources, the North Koreans donated 2,000 railway cars worth of material while thousands of Korean "volunteers" 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 to 70,000 Korean veterans that served in the PLA were sent back along with their weapons, and they would later play 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.

Korea divided (1945–1949)

On 8 September 1945, Lt. Gen. John R. Hodge of the United States arrived in Incheon to accept the Japanese surrender south of the 38th parallel. Appointed as military governor, General Hodge directly controlled South Korea via the United States Army Military Government in Korea (USAMGIK 1945–48). He established control by restoring to power the key Japanese colonial administrators and their Korean police collaborators. The USAMGIK refused to recognise the provisional government of the short-lived People's Republic of Korea (PRK) because he suspected it was communist. These policies, voiding popular Korean sovereignty, provoked civil insurrections and guerrilla warfare. On 3 September 1945, Lieutenant General Yoshio Kozuki, Commander, Japanese Seventeenth Area Army, contacted Hodge, telling him that the Soviets were south of the 38th parallel at Kaesong. Hodge trusted the accuracy of the Japanese Army report.

In December 1945, Korea was administered by a US–USSR Joint Commission, as agreed at the Moscow Conference (1945). The Koreans were excluded from the talks. The commission decided the country would become independent after a five-year trusteeship action facilitated by each régime sharing its sponsor's ideology. The Korean populace revolted; in the south, some protested, and some rose in arms; 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.

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.

The right-wing Representative Democratic Council, led by nationalist Syngman Rhee, opposed the Soviet–American trusteeship of Korea, arguing that after 35 years (1910–45) of Japanese colonial rule most Koreans opposed another foreign occupation. The USAMGIK decided to forego the five year trusteeship agreed upon in Moscow, given the 31 March 1948 United Nations election deadline to achieve an anti-communist civil government in the US Korean Zone of Occupation.

On 3 April what began as a demonstration commemorating Korean resistance to Japanese rule ended with the Jeju massacre of as many as 60,000 citizens by South Korean soldiers.

On 10 May, South Korea convoked their first national general elections that the Soviets first opposed, then boycotted, insisting that the US honor the trusteeship agreed to at the Moscow Conference.

North Korea held parliamentary elections three months later on 25 August 1948.

The resultant anti-communist South Korean government promulgated a national political constitution on 17 July 1948, elected a president, the American-educated strongman Syngman Rhee on 20 July 1948. The elections were marred by terrorism and sabotage resulting in 600 deaths. The Republic of Korea (South Korea) was established on 15 August 1948. In the Russian Korean Zone of Occupation, the USSR established a Communist North Korean government led by Kim Il-sung. President Rhee's régime expelled communists and leftists from southern national politics. Disenfranchised, they headed for the hills, to prepare for guerrilla war against the US-sponsored ROK Government.

As nationalists, both Syngman Rhee and Kim Il-Sung were intent upon reunifying Korea under their own political system. With Joseph Stalin and Mao Zedong fighting over the control of the Korean Peninsula, the North Koreans gained support from both the Soviet Union and the People's Republic of China. They escalated the continual border skirmishes and raids and then prepared to invade. South Korea, with limited matériel, could not match them. During this era, at the beginning of the Cold War, the US government assumed that all communists, regardless of nationality, were controlled or directly influenced by Moscow; thus the US portrayed the civil war in Korea as a Soviet hegemonic maneuver.

In October 1948, South Korean left-wing soldiers rebelled against the government's harsh clampdown in April on Jeju island in the Yeosu-Suncheon Rebellion.

The Soviet Union withdrew as agreed from Korea in 1948. U.S. troops withdrew from Korea in 1949, leaving the South Korean army relatively ill-equipped. On 24 December 1949, South Korean forces killed 86 to 88 people in the Mungyeong massacre and blamed the crime on communist marauding bands.

Course of the war

The conflict begins (June 1950)

After the US missions had left the People's Republic of China, CIA China station officer Douglas Mackiernan volunteered to remain and conduct spy operations. Afterward, he and a team of indigenous personnel then escaped China in a months-long horse trek across the Himalaya mountains; he was killed within miles of Lhasa. His team delivered the intelligence to headquarters that invasion was imminent. Thirteen days later on 25 June 1950, the North Korean People's Army (KPA) crossed the 38th parallel border and invaded South Korea. Mackiernan was posthumously awarded the CIA Intelligence Star for valor.

Under the guise of counter-attacking a South Korean provocation raid, the KPA crossed the 38th parallel behind artillery fire at dawn on Sunday 25 June 1950. The KPA said that Republic of Korea Army (ROK Army) troops, under command of the régime of the "bandit traitor Syngman Rhee", had crossed the border first, and that they would arrest and execute Rhee. Both Korean armies had continually harassed each other with skirmishes and each continually staged raids across the 38th parallel border.

On 27 June, Rhee evacuated from Seoul with government officials. Rhee ordered the Bodo League massacre, which started on 28 June.

On 28 June, South Korea bombed the bridge across the Han River to stop the North Korean army.

Early on in the fighting, South Korea put its forces under the authority of the United Nations Command (Korea).

Factors in US intervention

One facet of the changing attitude toward Korea and whether to get involved was Japan. Especially after the fall of China to the Communists, "…Japan itself increasingly appeared as the major East Asian prize to be protected". US 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 that dealt with South Korea directly as a national interest, its proximity to Japan pushed South Korea to the fore. "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 US policy toward Japan." The United States wanted to shore up Japan to make it a viable counterweight against the Soviet Union and China, and Korea was seen as integral to that end.

The other important part of committing to intervention lay in speculation about Soviet action in the event that the United States intervene. 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 US 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]". In Truman’s mind, this aggression, if left unchecked, would start a chain reaction that would destroy the United Nations and give the go ahead to further Communist aggression elsewhere. Korea was where a stand had to be made, the difficult part was how. The UN Security council approved the use of force to help the South Koreans and the US immediately began using air and naval forces in the area to that end. The Administration still refrained from committing on the ground because some advisors believed the North Koreans could be stopped by air and naval power alone. Also, it was still uncertain if this was a clever ploy by the Soviet Union to catch the US unawares or just a test of US resolve. The decision to commit ground troops and to intervene eventually became viable when a communiqué was received on 27 June from the Soviet Union that alluded it would not move against US forces in Korea. "This opened the way for the sending of American ground forces, for it now seemed less likely that a general war—with Korea as a preliminary diversion—was imminent". With the Soviet Union’s tacit agreement that this would not cause an escalation, the United States now could intervene with confidence that other commitments would not be jeopardized.

United Nations Security Council Resolutions

The USSR challenged the legitimacy of the war for several reasons. The ROK Army intelligence upon which Resolution 83 was based came from US Intelligence; North Korea was not invited as a sitting temporary member of the UN, which violated UN Charter Article 32; and the Korean conflict was beyond UN Charter scope, because the initial north–south border fighting was classed as a civil war. The Soviet representative boycotted the UN to prevent Security Council action, and to challenge the legitimacy of the UN action; legal scholars posited that deciding upon an action of this type required the unanimous vote of the five permanent members.

Comparison of military forces

In contrast, the ROK Army defenders were vastly unprepared, and the political establishment in the south, while well aware of the threat to the north, were unable to convince American administrators of the reality of the threat. In ''South to the Naktong, North to the Yalu'' (1961), R.E. Appleman reports the ROK forces' low combat readiness 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 US 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 invasion time, but there were large US garrisons and air forces in Japan.

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

United Nations response (July – August 1950)

On Saturday, 24 June 1950, US Secretary of State Dean Acheson informed President Truman by telephone, "Mr. President, I have very serious news. The North Koreans have invaded South Korea." Truman and Acheson discussed a US invasion response with defense department principals, who agreed that the United States was obligated to repel military aggression, paralleling it with Adolf Hitler's 1930s aggressions, and said that the mistake of appeasement must not be repeated. In his autobiography, President Truman acknowledged that 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):

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President Truman announced that the US would counter "unprovoked aggression" and "vigorously support the effort of the [UN] security council to terminate this serious breach of peace." Because the US had sent the Seventh Fleet to "neutralize" the Taiwan Strait, Chinese premier Zhou Enlai criticized both the UN and US initiatives as "armed aggression on Chinese territory."

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. 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. Overhead, the KPAF shot down 18 USAF fighters and 29 bombers; the USAF shot down five KPAF fighters.

By August, the KPA had 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 that he was responsible for the KPA's atrocities. By September, the UN Command controlled only the Pusan perimeter, enclosing only about 10% of Korea, in a line partially defined by the Nakdong River.

Although Kim's early successes had led him to predict that he would end the war by the end of August, Chinese leaders were more pessimistic. To counter the possibility of American invasion, Zhou Enlai secured a Soviet commitment to have the USSR 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)

In the resulting Battle of Pusan Perimeter (August–September 1950), the US 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 materiel to the KPA, the USAF destroyed logistics depots, petroleum refineries, and harbors, while the US Navy air forces attacked transport hubs. Consequently, the over-extended KPA could not be supplied throughout the south.

Meanwhile, US garrisons in Japan continually dispatched soldiers and materiel to reinforce defenders in the Pusan Perimeter. Tank battalions deployed to Korea directly from the United States 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)

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 Inchon, well over 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.

Soon after the war began, General MacArthur had begun planning a landing at Incheon, but the Pentagon opposed him. When authorized, he activated a combined United States Army, United States 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 the 15 September attack date, 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"—3rd Battalion, 7th Cavalry Regiment, and two 70th Tank Battalion units (Charlie Company and the Intelligence–Reconnaissance Platoon)— effected the "Pusan Perimeter Breakout" through 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 Inchon 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)

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."

On 30 September Zhou Enlai warned the United States that it 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 had allowed Chinese communist forces to successfully escape Chiang Kai-shek's Encirclement Campaigns in the 1930s. North Korean commanders did not utilize these tactics effectively.

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 United States 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 the only two combat jumps during the Korean War on 20 October 1950 at Sunchon and Sukchon, North Korea. 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.

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)

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 protect the Nationalist Republic of China (Taiwan) from 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.

On 20 August 1950, Premier Zhou Enlai informed the United Nations that "Korea is China's neighbor... The Chinese people cannot but be concerned about a solution of the Korean question". Thus, via 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.

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 to request 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 2–5 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 United States in Korea. Mao strongly supported intervention, and Zhou was one of the few Chinese leaders who firmly supported him. After General Lin Biao refused Mao's offer to command Chinese forces in Korea (citing poor health), Mao called General Peng Dehuai to Beijing to hear his views. After listening to both sides' arguments, Peng supported Mao's position, and the Politburo agreed to intervene in Korea. Later, the Chinese claimed that US bombers had violated PRC national airspace while en route to bomb North Korea ''before'' China intervened. On 8 October 1950, Mao Zedong redesignated the PLA North East Frontier Force as the Chinese People's Volunteer Army (PVA).

In order to enlist Stalin's support, Zhou traveled to Stalin's summer resort on the Black Sea on 10 October. Stalin initially agreed to send military equipment and ammunition, but warned Zhou that the USSR'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 materiel, 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.

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 from An-tung, Manchuria to the combat zone in some 19 days. Another division night-marched a circuitous mountain route, averaging 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.

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 US. 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. After decimating the ROK II Corps at the Battle of Onjong, the first confrontation between Chinese and US military occurred on 1 November 1950; deep in North Korea, thousands of soldiers from the PVA 39th Army encircled and attacked the US 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.

The UN Command, however, were unconvinced that the Chinese had openly intervened due to the sudden Chinese withdrawal. On 24 November, the Home-by-Christmas Offensive was launched with the US Eighth Army advancing in northwest Korea, while the US X Corps were attacking 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 over-ran 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 US 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 (27–9 November). On 27 November at the Korean eastern front, a US 7th Infantry Division Regimental Combat Team (3,000 soldiers) and the US 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 they managed to escape under Air Force and X Corps support fire—albeit with some 15,000 collective casualties.

By 30 November, the PVA 13th Army Group managed to expel the US 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. The UN morale hit rock bottom when commanding General Walton Walker of the US Eighth Army was killed on 23 December 1950 in an automobile accident. In the northeast Korea by 11 December, the US 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 US Eighth Army to the south.

During the Hungnam evacuation, about 193 shiploads of UN Command forces and materiel (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 only 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.

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

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 was forced to recoil from pressing the attack beyond Seoul; food, ammunition, and materiel 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 gradually proceeded while fully exploiting the UN Command's air superiority, concluded with the UN reaching the Han River and recapturing Wonju near Seoul.

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. Units of the US 2nd Infantry Division 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. The battle saw 5,600 Korean, American and French defeat a numerically superior Chinese force. Surrounded on all sides, the US 2nd Infantry Division Warrior Division’s 23rd Regimental Combat Team with an attached French Battalion was hemmed in by more than 25,000 Chinese Communist Forces. 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. The allies fought at odds of roughly 15 to 1.

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 years' 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 urgent need for air cover, especially over supply lines. Apparently impressed by the Chinese war effort, Stalin finally 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 that they had nothing to eat, no bullets to shoot, and no 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 methods of supply, but these efforts were never completely sufficient. At the same time, large-scale air defense training programs were carried out, and the Chinese Air Force began to participate 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 had 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 or not to use nuclear weapons should be his own 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 US Constitution. A popular criticism of MacArthur was that he never spent a night in Korea, and directed the war from the safety of Tokyo.

General Ridgway was appointed Supreme Commander, Korea; he regrouped the UN forces for successful counterattacks, while General James Van Fleet assumed command of the US 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 ("Rakkasans") second of two combat jumps were 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 US X Corps in the east. After initial success, they were halted by 20 May. At month's end, the US 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)

The principal battles of the stalemate include the Battle of Bloody Ridge (18 August – 15 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 (10–8 June 1953), the Battle of the Hook (28–9 May 1953) and the Battle of Pork Chop Hill (23 March – 16 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 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 Shanyang 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 foreseeable 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)

In 1952 the US 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, US, 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 lay in the pre-war ROK, but now is in the DPRK. The United Nations Command, supported by the United States, the North Korean 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. For his part, ROK President Rhee attacked the peace proceedings. 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 (July–November 1954) was conducted to allow combatant countries to exchange their dead. The remains of 4,167 US Army and US 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 ROK 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)

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.

At the same time, there have been numerous incursions and acts of aggression from North Korea across the border, most notably the axe murder incident of 1976. Four infiltration tunnels leading to Seoul have been uncovered. In 2010, North Korea fired artillery shells on Yeonpyeong island, killing two military personnel and two civilians.

Characteristics

Casualties

According to the data from the US Department of Defense, the United States had suffered 33,686 battle deaths, along with 2,830 non-battle deaths during the Korean War and 8,176 missing in action. Western sources estimate the PVA had suffered between 100,000 to 1,500,000 deaths (most estimate some 400,000 killed), while the KPA had suffered between 214,000 to 520,000 deaths (most estimate some 500,000). Between some 245,000 to 415,000 South Korean civilian deaths were also suggested, and the entire civilian casualty during the war were estimated from 1,500,000 to 3,000,000 (most sources estimate some 2,000,000 killed).

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 21,400 captured during the war. Among those captured, about 14,000 defected to Taiwan while the other 7,110 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. In return, the Chinese and North Koreans estimated that about 390,000 soldiers from United States, 660,000 soldiers from South Korea and 29,000 other UN soldiers were "eliminated" from the battlefield.

Armored warfare

Initially, North Korean armor dominated the battlefield with Soviet T-34-85 medium tanks designed during the Second World War. The KPA's tanks confronted a tankless ROK Army armed with few modern anti-tank weapons, including American World War II–model 2.36-inch (60 mm) M9 bazookas, effective only against the 45 mm side armor of the T-34-85 tank. The US forces arriving in Korea were equipped with light M24 Chaffee tanks (on occupation duty in nearby Japan) that also proved ineffective against the heavier KPA T-34 tanks.

During the initial hours of warfare, some under-equipped ROK Army border units used American 105 mm howitzers as anti-tank guns to stop the tanks heading the KPA columns, firing high-explosive anti-tank ammunition (HEAT) over open sights to good effect; at the war's start, the ROK Army had 91 howitzers, but lost most to the invaders.

Countering the initial combat imbalance, the UN Command reinforcement materiel included heavier US M4 Sherman, M26 Pershing, M46 Patton, and British Cromwell and Centurion tanks that proved effective against North Korean armor, ending its battlefield dominance. Unlike in the Second World War (1939–45), in which the tank proved a decisive weapon, the Korean War featured few large-scale tank battles. The mountainous, heavily forested terrain prevented large masses of tanks from maneuvering. In Korea, tanks served largely as infantry support and mobile artillery pieces.

Aerial warfare

The Korean War was the first war in which jet aircraft played a central role. 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, 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 balance would shift with the arrival of the swept wing Soviet MiG-15 Fagot.

The Chinese intervention in late October 1950 bolstered the Korean People's Air Force (KPAF) of North Korea with the MiG-15 Fagot, one of the world's most advanced jet fighters. The fast, heavily armed MiG outflew first-generation UN jets such as the American F-80 and Australian and British Gloster Meteors, posing a real threat to B-29 Superfortress bombers even under fighter escort. Soviet Air Force pilots flew missions for the North to learn the West's aerial combat techniques. This direct Soviet participation is a ''casus belli'' that the UN Command deliberately overlooked, lest the war for the Korean peninsula expand, as the US initially feared, to include three communist countries—North Korea, the Soviet Union, and China—and so escalate to atomic warfare.

The USAF moved quickly to counter the MiG-15, with three squadrons of its most capable fighter, the F-86 Sabre, arriving in December 1950. Although the MiG's higher service ceiling— vs. —could be advantageous at the start of a dogfight, in level flight, both swept wing designs attained comparable maximum speeds of around . The MiG climbed faster, but the Sabre turned and dived better. The MiG was armed with one 37 mm and two 23 mm cannons, while the Sabre carried six .50 caliber (12.7 mm) machine guns aimed with radar-ranged gunsights.

By early 1951, the battle lines were established and changed little until 1953. 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.

UN forces gradually gained air superiority in the Korean theater. This was decisive for the UN: first, for attacking into the peninsular north, and second, for resisting the Chinese intervention. North Korea and China also had jet-powered air forces; their limited training and experience made it strategically untenable to lose them against the better-trained UN air forces. Thus, the US and USSR fed materiel to the war, battling by proxy and finding themselves virtually matched, technologically, when the USAF deployed the F-86F against the MiG-15 late in 1952.

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. An uncited alternative source claims only 379 Sabre kills. 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, as more recent US figures state only 230 losses out of 674 F-86s deployed to Korea. The differing tactical roles of the F-86 and MiG-15 may have contributed to the disparity in losses: MiG-15s primarily targeted B-29 bombers and ground-attack fighter-bombers, while F-86s targeted the MiGs.

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 North Korea

As a result, eighteen of North Korea's cities were more than 50% destroyed. The war's highest-ranking American POW, US Major General William F. Dean, reported that most of the North Korean cities and villages he saw were either ruins or snow-covered wastelands.

As well as conventional bombing, the Communist side claimed that the USA had used biological weapons.

Naval warfare

Because neither Korea's navies were large, the Korean War featured few naval battles; mostly the combatant navies served as naval artillery for their in-country armies. A skirmish between North Korea and the UN Command occurred on 2 July 1950; the US 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.

During most of the war, the UN navies patrolled the west and east coasts of North Korea and sank supply and ammunition ships to deny the sea to North Korea. Aside from very occasional gunfire from North Korean shore batteries, the most threat to US and UN navy ships were from magnetic mines the North Koreans employed for defensive purposes.

The USS ''Juneau'' sank ammunition ships that had been present in her previous battle. 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.

U.S. threat of atomic warfare

President Truman did not immediately threaten nuclear warfare after the October 1950 Chinese intervention, but, 45 days later, remarked about the possibility of using it after the PVA repelled the UN Command from North Korea.

In ''The Origins of the Korean War'' (1981, 1990), US historian Bruce Cumings reports that in a 30 November 1950 press conference, President Truman's allusions to attacking the KPA with nuclear weapons "was a threat based on contingency planning to use the bomb, rather than the faux pas so many assumed it to be." On 30 November 1950, the USAF Strategic Air Command was ordered to "augment its capacities, and that this should include atomic capabilities."

The Indian Ambassador, K. Madhava Panikkar, reports "that Truman announced that he was thinking of using the atom bomb in Korea. But the Chinese seemed totally 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 very useful to the leaders of the Revolution, to enable them to keep up the tempo of their activities."

President Truman remarked that his government was actively considering using the atomic bomb to end the war in Korea but that only he—the US President—commanded atomic bomb use, and that he had not given authorization. The matter of atomic warfare was solely a US decision, not the collective decision of the UN. 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 US's forgoing atomic warfare was not because of "a disinclination by the USSR and PRC 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 US fought China, who then might persuade the USSR to conquer Western Europe.

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 encompassinging the next weeks and months of warfare.

In the first scenario: If the PVA continued attacking in full and the UN Command is forbidden to blockade and bomb China, and without Nationalist Chinese reinforcements, and without an increase in US 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 have blockaded China and have effective aerial reconnaissance and bombing of the Chinese interior, and the Nationalist Chinese soldiers are maximally exploited, and tactical atomic bombing is to hand, then the UN forces could hold positions deep in North Korea.

In the third scenario: if the PRC 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 US 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.

In 1951, the US escalated closest to atomic warfare in Korea. Because the PRC had 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 US effected ''Operation Hudson Harbor'' to establish 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."

War crimes

Civilian deaths and massacres

In occupied areas, North Korean Army political officers purged South Korean society of its intelligentsia by assassinating every educated person—academic, governmental, religious—who might lead resistance against the North; the purges continued during the NPA retreat. Immediately after the invasion in June 1950 the South Korean Government ordered the nation-wide "pre-emptive apprehension" of politically suspect or disloyal citizens.

The military police and right-wing paramilitary (civilian) armies executed thousands of left-wing and communist political prisoners at Daejeon Prison and in the Jeju Uprising (1948–49). The Americans on the island documented the events, but never intervened.

US diplomat Gregory Henderson, then in Korea, calculates some 100,000 pro-North political prisoners were killed and buried in mass graves. The South Korean Truth and Reconciliation Commission has compiled reports of hundreds of thousands of civilian killings before and during the war.

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. US troops acted under a "shoot-first-ask-questions-later" policy against any civilian refugee approaching US battlefield positions, a policy that led US Soldiers to kill between 8 and 400 civilians at No Gun Ri (26–29 July 1950) in central Korea because they believed some of the refugees killed to be North Korean soldiers in disguise.

The Korean armies forcibly conscripted available civilian men and women to their war efforts. In ''Statistics of Democide'' (1997), Prof. R. J. Rummel reports that the North Korean Army conscripted some 400,000 South Korean citizens. The South Korean Government reported that the North abducted some 83,000 citizens before the US recaptured Seoul in September 1950; the North says they defected.

Bodo League anti–communist massacre

To outmaneuver a possible fifth column in the Republic of Korea, President Syngman Rhee's régime assassinated its "enemies of the state"—South Koreans who are allegedly communists, pro-North Korea, or leftist—by first imprisoning them for political re-education in the ''Gukmin Bodo Ryeonmaeng'' (National Rehabilitation and Guidance League, also known as the Bodo League). The true purpose of the anti–communist Bodo League, abetted by the United States Army Military Government in Korea (USAMGIK), was the régime's assassination of some 10,000 to 100,000 "enemies of the state" whom they dumped in trenches, mines, and the sea, before and after the 25 June 1950 North Korean invasion. Contemporary calculations report some 200,000 to 1,200,000. USAMGIK officers were present at one political execution site; at least one US officer sanctioned the mass killings of political prisoners whom the North Koreans would have freed after conquering the peninsular south.

The South Korean Truth and Reconciliation Commission reports that petitions requesting explanation of the summary execution of leftist South Koreans outnumber, six-to-one, the petitions requesting explanation of the summary execution of rightist South Koreans. These data apply solely to South Korea, because North Korea is not integral to the Truth and Reconciliation Commission. The father of Bodo League massacre survivor Kim Jong-chol was press-ganged to work with the KPA and later executed by the Rhee Government as a collaborator; his grandparents and a seven-year-old sister also were assassinated. About his experience in Namyangju city, he says:

USAMGIK officers photographed the mass killings at Daejon city in central South Korea, where the Truth Commission believe some 3,000 to 7,000 people were shot and buried in mass graves in early July 1950. Other declassified records report that a US Army Lieutenant Colonel approved the assassination of 3,500 political prisoners by the ROK Army unit to which he was military advisor when the KPA reached the southern port city of Pusan. US diplomats reported having urged the Rhee régime's restraint against its political opponents, and that the USAMGIK, who formally controlled the peninsular south, did not halt the mass assassinations.

Prisoners of war

The KPA killed POWs at the battles for Hill 312, Hill 303, the Pusan Perimeter, and Daejeon—discovered during early after-battle mop-up actions by the UN forces. Later, a US 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 Korean counterparts, mass starvation and diseases swept through the Chinese run POW camps during the winter of 1950–51. About 43 percent of all US 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 the lack of competent logistics system. The UN POWs, however, disputed the claim by pointing out that most of the Chinese camps were located near the easily supplied Sino-Korean border, and that starvation was used to force the prisoners to accept the communism indoctrinations programs, which were running in full swing after the starvation was over. The North Korean Government reported some 70,000 ROK Army POWs; 8,000 were repatriated. South Korea repatriated 76,000 Korean People's Army POWs. Besides the 12,000 UN Command forces POWs dead in captivity, the KPA might have press-ganged some 50,000 ROK POWs into the North Korean military. Per the South Korean Ministry of Defense, there remained some 560 Korean POWs detained in North Korea in 2008; from 1994 until 2009, some 79 ROK POWs escaped the North.

The North Korean Government denied having POWs from the Korean War, and, via the Korean Central News Agency, reported that the UN forces killed some 33,600 KPA POWs; that on 19 July 1951, in POW Camp No. 62, some 100 POWs were killed as machine-gunnery targets; that on 27 May 1952, in the 77th Camp, Koje Island (now in Geoje), the ROK Army incinerated with flamethrowers some 800 KPA POWs who rejected "voluntary repatriation" south, and instead demanded repatriation north.

Starvation

Aftermath

Effect on China

China emerged from the Korean War united by a sense of national pride, despite the war's enormous costs. The Chinese people were educated to believe that the war was initiated by the United States and Korea, and not by a fraternal communist state in the north. In Chinese propaganda, the Chinese war effort was portrayed and accepted 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 in order to promote the image of the PLA and the CCP. 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.

Defection

Proxy war

DMZ

Racial integration of U.S. Forces

Turkey

Post-war economies

In the 1990s North Korea faced significant economic disruptions. The North Korean famine is believed to have killed as many as 2.5 million people. The CIA World Factbook estimates North Korea's GDP (Purchasing power parity (PPP)) is $40 billion, which is 3.0% of South Korea's $1.196 trillion GDP (PPP). North Korean personal income is $1,800 per capita, which is 7.0% of the South Korean $24,500 per capita income.

ROK Anti-communism

ROK Anti-Americanism sentiments

"G.I. Babies" and U.S. immigration law

The U.S. Immigration Act of 1952 removed race as a limiting factor in immigration, 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.

Popular culture

See also

Notes

References

Further reading

Combat studies, soldiers

Origins, politics, diplomacy

Reference sources

Primary sources

External links

Historical

Media

Organizations

Memorials

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