The Korean War (25 June 1950 – 27 July 1953) was an armed conflict fought on the Korean Peninsula between North Korea (Democratic People's Republic of Korea; DPRK) and South Korea (Republic of Korea; ROK) and their allies. North Korea was supported by China and the Soviet Union, while South Korea was supported by the United Nations led by the United States under the auspices of the United Nations Command (UNC). After the end of World War II in 1945, Korea, which had been a Japanese colony for 35 years, was divided by the Soviet Union and the United States into two occupation zones at the 38th parallel, with plans for a future independent state. The zones formed their own governments in 1948 due to political disagreements. North Korea was led by Kim Il Sung in Pyongyang, and South Korea by Syngman Rhee in Seoul; both claimed to be the sole legitimate government of all of Korea. Both sides engaged in extensive border clashes while Rhee's government suppressed communist uprisings at Jeju and Yeosu-Suncheon. On 25 June 1950, North Korea's Korean People's Army (KPA) launched an invasion of South Korea. In the absence of the Soviet Union's representative, the UN Security Council denounced the invasion, calling on member states to help repel the invasion. UN forces under the unified command comprised 21 countries, with the US providing around 90% of military personnel. On 27 June 1950 President Harry S. Truman ordered US air and sea forces to aid South Korea. Seoul was captured by the KPA on 28 June, and by early August, the Republic of Korea Army (ROKA) and its allies were nearly defeated, holding onto only the Pusan Perimeter in the peninsula's southeast. On 15 September, UN forces landed at Inchon near Seoul, cutting off KPA troops and supply lines. UN forces broke out from the perimeter on 18 September, recaptured Seoul, and invaded North Korea in October, capturing Pyongyang and advancing towards the Yalu River (border with China). On 19 October, the Chinese People's Volunteer Army (PVA) crossed the Yalu and entered the war on the side of the North. UN forces retreated from North Korea in December, following the PVA's first and second offensive. Communist forces captured Seoul again in January 1951 before losing it to a UN counter-offensive two months later. After an abortive Chinese spring offensive, UN forces retook territory roughly up to the 38th parallel. Armistice negotiations began in July 1951, but dragged on as the fighting became a war of attrition and the North suffered devastating damage from UN bombing, destroying virtually all of North Korea's major cities. Combat ended on 27 July 1953 with the signing of the Korean Armistice Agreement, which allowed the exchange of prisoners and created a 4-kilometre wide (2.5 mile) Demilitarized Zone (DMZ) along the frontline, with a Joint Security Area at Panmunjom. The industrial warfare was defined by armored offensives, with the North's initial invasion and later by UN forces, tunnel warfare by Chinese forces, and the first large jet aircraft battles. The conflict caused around one million military deaths and an estimated 1.5 million to 3 million civilian deaths. Alleged war crimes include the mass killing of alleged communists by South Korea, the Seoul National University Hospital massacre by North Korea, and the carpet bombing of North Korea by the UNC. North Korea became one of the most heavily bombed countries in history. No peace treaty has been signed; the Korean conflict remains a frozen conflict, which has occasionally flared, such as in the 1966–1969 DMZ Conflict.
Names
In South Korea, the war is usually referred to as the "625 War" (6·25 전쟁; 六二五戰爭; Yugio jeonjaeng), the "625 Upheaval" (6·25 동란; 六二五動亂; Yugio dongnan), or simply "625", reflecting the date of its commencement on 25 June. In North Korea, the war is officially referred to as the "Fatherland Liberation War" (조국해방전쟁; Choguk haebang chŏnjaeng) or commonly the "Chosŏn [Korean] War" (조선전쟁; Chosŏn chŏnjaeng). In the United States, the war was initially described by President Harry S. Truman as a "police action" as the US never formally declared war and its military actions in Korea were conducted under the auspices of the UN flag. It has sometimes 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 relative to World War II and the Vietnam War. In China, the segment of the war after the intervention of the People's Volunteer Army is commonly and officially known as the "War to Resist America and Assist Korea" (Chinese: 抗美援朝战争; pinyin: Kàngměi Yuáncháo Zhànzhēng), while the segment preceding that is officially called the "Korean Civil War" (simplified Chinese: 朝鲜内战; traditional Chinese: 朝鮮內戰; pinyin: Cháoxiǎn Nèizhàn). The term "Chosŏn War" (simplified Chinese: 朝鲜战争; traditional Chinese: 朝鮮戰爭; pinyin: Cháoxiǎn Zhànzhēng) is sometimes used unofficially. The term "Hán (Korean) War" (Chinese: 韓戰; pinyin: Hán Zhàn) is most used in Taiwan (Republic of China), Hong Kong and Macau.
Background
Japanese colonization (1910–1945)
Korea was a colony ruled by the Empire of Japan from 1910 to 1945. The Empire of Japan diminished China's influence over Korea in the First Sino-Japanese War (1894–95). A decade later, after defeating Imperial Russia in the Russo-Japanese War, Japan made the Korean Empire its protectorate with the Eulsa Treaty in 1905, and then annexed it with the Japan–Korea Treaty of 1910. Many Korean nationalists fled the country. The Provisional Government of the Republic of Korea was founded in 1919 in the Beiyang government. It failed to achieve international recognition, failed to unite the nationalist groups, and had a fractious relationship with its US-based founding president, Syngman Rhee. The Chinese nationalist National Revolutionary Army and the communist People's Liberation Army (PLA) 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 (1941–1945). The communists, led by Kim Il Sung, among others, fought the Japanese in Korea and Manchuria. At the Tehran Conference in 1943 and the Yalta Conference in February 1945, the Soviet Union promised to join the Allies in the Pacific War within three months of the victory in Europe. On 8 August 1945, the USSR declared war on Japan and invaded Manchuria. On 10 August, Soviet forces entered northern Korea and had secured most major cities in the north by 24 August, as Japanese resistance was light. Having fought Japan on Korean soil, the Soviet forces were well received by Koreans. Imperial Japanese rule of Korea officially ended when Japan surrendered to the Allies on 15 August 1945, following the atomic bombings of Hiroshima and Nagasaki.
Division of Korea (1945)
At the Cairo Conference in 1943, China, the UK, and the US decided that "in due course, Korea shall become free and independent". As World War II drew to a close, on 11 August 1945 two American military officials in Washington – US Colonels Dean Rusk and Charles H. Bonesteel III – chose an invisible line across the former Japanese colony, the 38th Parallel, for the division of Korea into two occupation zones, north and south, Soviet and American. This was incorporated into US General Order No. 1, which responded to the Japanese surrender on 15 August. Joseph Stalin, however, maintained his wartime policy of cooperation, and on 16 August, the Red Army halted at the 38th parallel for three weeks to await the arrival of US forces. In explaining the choice of the 38th parallel, US Colonel Dean Rusk observed that, "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".
=== Joint US-Soviet occupation (1945–1948) === On 7 September 1945, General Douglas MacArthur issued Proclamation No. 1 to the people of Korea, announcing US military control over Korea south of the 38th parallel and establishing English as the official language during military control. On 8 September, US Lieutenant General John R. Hodge arrived in Incheon to accept the Japanese surrender south of the 38th parallel. Appointed as military governor, Hodge directly controlled South Korea as head of the US Army Military Government in Korea (USAMGIK 1945–48). In December 1945, Korea was administered by the US–Soviet Union Joint Commission, as agreed at the Moscow Conference, to grant independence after a five-year trusteeship. Waiting five years for independence was unpopular among Koreans, and riots broke out. The Communist Party supported the trusteeship, while Kim Ku and Syngman Rhee led the anti-trusteeship movement against both the US Army Military Government in Korea and the Soviet military administration. To contain them, the USAMGIK banned strikes on 8 December and outlawed the PRK Revolutionary Government and People's Committees on 12 December. Following further civilian unrest, the USAMGIK declared martial law. Citing the inability of the Joint Commission to make progress, the United Nations (UN) decided to hold an election under UN auspices to create an independent Korea, as stated in UN General Assembly Resolution 112. The Soviet authorities and Korean communists refused to participate in the election. The final attempt to establish a unified government was thwarted by North Korea's refusal. Due to concerns about division caused by an election without North Korea's participation, many South Korean politicians boycotted it. The 1948 South Korean general election was held in May. The resultant South Korean government promulgated a national political constitution on 17 July and elected Syngman Rhee as president on 20 July. The Republic of Korea (South Korea) was established on 15 August 1948. In the Soviet-Korean Zone of Occupation, the Soviets agreed to the establishment of a communist government led by Kim Il Sung. The Democratic People's Republic of Korea (North Korea) was established on 10 July 1948. The 1948 North Korean parliamentary elections took place in August. The Soviet Union withdrew its forces in 1948 and the US in 1949.
=== Chinese Civil War (1945–1949) === With the end of the war with Japan, the Chinese Civil War resumed in earnest between the Communists and the Nationalist-led government. 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 supplies while thousands of Koreans served in the Chinese 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. As a token of gratitude, between 50,000 and 70,000 Korean veterans who 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.
=== Communist insurgency in South Korea (1948–1950) === By 1948, a North Korea-backed insurgency had broken out in the southern half of the peninsula. This was exacerbated by the undeclared border war between the Koreas, which saw division-level engagements and thousands of deaths on both sides. The ROK was almost entirely trained and focused on counterinsurgency, rather than conventional warfare. They were equipped and advised by a force of a few hundred American officers, who were successful in helping the ROKA to subdue guerrillas and hold its own against North Korean military (Korean People's Army, KPA) forces along the 38th parallel. Approximately 8,000 South Korean soldiers and police officers died in the insurgent war and border clashes. The first socialist uprising occurred without direct North Korean participation, though the guerrillas still professed support for the northern government. Beginning in April 1948 on Jeju Island, the campaign saw arrests and repression by the South Korean government in the fight against the South Korean Labor Party, resulting in 30,000 violent deaths, among them 14,373 civilians, of whom 2,000 were killed by rebels and 12,000 by ROK security forces. The Yeosu–Suncheon rebellion overlapped with it, as several thousand army defectors waving red flags massacred right-leaning families. This resulted in another brutal suppression by the government and between 2,976 and 3,392 deaths. By May 1949, both uprisings had been crushed. Insurgency reignited in the spring of 1949 when attacks by guerrillas in the mountainous regions (buttressed by army defectors and North Korean agents) increased. Insurgent activity peaked in late 1949 as the ROKA engaged so-called People's Guerrilla Units. Organized and armed by the North Korean government, and backed by 2,400 KPA commandos who had infiltrated through the border, these guerrillas launched an offensive in September aimed at undermining the South Korean government and preparing the country for the KPA's arrival in force. This offensive failed. However, the guerrillas were now entrenched in the Taebaek-san region of the North Gyeongsang Province and the border areas of the Gangwon Province. While the insurgency was ongoing, the ROKA and KPA engaged in battalion-sized battles along the border, starting in May 1949. Border clashes between South and North continued on 4 August 1949, when thousands of North Korean troops attacked South Korean troops occupying territory north of the 38th parallel. The 2nd and 18th ROK Infantry Regiments repulsed attacks in Kuksa-bong, and KPA troops were "completely routed". Border incidents decreased by the start of 1950. Meanwhile, counterinsurgencies in the South Korean interior intensified; persistent operations, paired with worsening weather, denied the guerrillas sanctuary and wore away their fighting strength. North Korea responded by sending more troops to link up with insurgents and build more partisan cadres; North Korean infiltrators had reached 3,000 soldiers in 12 units by the start of 1950, but all were destroyed or scattered by the ROKA. On 1 October 1949, the ROKA launched a three-pronged assault on the insurgents in South Cholla and Taegu. By March 1950, the ROKA claimed 5,621 guerrillas killed or captured and 1,066 small arms seized. This operation crippled the insurgency. Soon after, North Korea made final attempts to keep the uprising active, sending battalion-sized units of infiltrators under the commands of Kim Sang-ho and Kim Moo-hyon. The first battalion was reduced to a single man over the course of engagements by the ROKA 8th Division. The second was annihilated by a two-battalion hammer-and-anvil maneuver by units of the ROKA 6th Division, resulting in a toll of 584 KPA guerrillas (480 killed, 104 captured) and 69 ROKA troops killed, plus 184 wounded. By the spring of 1950, guerrilla activity had mostly subsided; the border, too, was calm.
=== Prelude to war (1950) === By 1949, South Korean and US military actions had reduced indigenous communist guerrillas in the South from 5,000 to 1,000. However, Kim Il Sung believed widespread uprisings had 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 persuade him. Kim and second-in-command Pak Hon-yong tried to enlist Soviet ambassador Terentii Shtykov. Kim met with the ambassador on 12 August 1949; Shtykov said that an outright invasion was out of the question unless South Korea attacked first and that he only willing to consider a limited operation targeting the Ongjin peninsula. Mun Il visited Soviet chargé d'affaires Grigory Tunkin on 3 September 1949. Tunkin's report to the Soviet government was more neutral than previous Soviet diplomats, who were more skeptical. Stalin initially did not think the time was right for a war in Korea. PLA forces were still embroiled in the Chinese Civil War, while US forces remained stationed in South Korea. After learning about Kim and Pak's plans, he told Tunkin to talk to Kim to produce an assessment of the South Korean and North Korean armed forces. After assessing both sides, Tunkin suggested against an invasion, to which Stalin agreed to and also banned the limited strike on the Ongjin peninsula. Kim continued his insistence on an invasion. On 17 January 1950, he told Soviet diplomats that South Korea needed to be liberated. By 1950, Stalin was more open to suggestions and believed that the strategic situation had changed: PLA forces under Mao Zedong had secured final victory, US forces had withdrawn from Korea, and the Soviets had detonated their first nuclear bomb, breaking the US monopoly. As the US had not directly intervened to stop the communists in China, Stalin calculated they would be even less willing to fight in Korea, which had less strategic significance. The Soviets had cracked the codes used by the US to communicate with their embassy in Moscow, and reading dispatches convinced Stalin that Korea did not have the importance to the US that would warrant a nuclear confrontation. On 30 January 1950, Stalin telegraphed Shtykov, saying that any invasion "would need extensive preparations" and that "it should be organized without taking too big a risk", effectively giving the green light for preparations. Stalin began a more aggressive strategy in Asia based on these developments, including promising economic and military aid to China through the Sino-Soviet Treaty of Friendship, Alliance and Mutual Assistance. Kim spent almost a month in the Soviet Union from 30 March to 25 April, during which invasion plans were finalized. In April 1950, Stalin permitted Kim to attack the government in the South, under the condition that Mao would agree to send reinforcements if needed. For Kim, this was the fulfillment of his goal to unite Korea. Stalin made it clear Soviet forces would not openly engage in combat, to avoid a direct war with the United States. Kim met with Mao in May 1950 and differing historical interpretations of the meeting have been put forward. According to Barbara Barnouin and Yu Changgeng, Mao agreed to support Kim despite concerns of American intervention, as China desperately needed the economic and military aid promised by the Soviets. Kathryn Weathersby cites Soviet documents which said Kim secured Mao's support. According to Park, Mao told Kim that "if the Americans would enter the war, China will help North Korea with troops". Along with Mark O'Neill, she says this accelerated Kim's war preparations. Chen Jian argues Mao never seriously challenged Kim's plans and Kim had every reason to inform Stalin that he had obtained Mao's support. Citing more recent scholarship, Zhao Suisheng contends Mao did not approve of Kim's war proposal and requested verification from Stalin, who did so via a telegram. Mao accepted the decision made by Kim and Stalin to unify Korea but cautioned Kim over possible US intervention. The coming Korean War was one of three wars that the Soviet and Chinese leaders had planned across East Asia in 1950. The first was a North Korean invasion of South Korea, which was to be backed by Chinese forces if necessary; they also planned a Chinese invasion of Taiwan later that year, and a Viet Minh revolution in Vietnam, which was to be backed by Chinese advisors and weaponry. Kim told his inner circle about the preparations, including Pak Hon-yong, Aleksei Hegay, Supreme People's Assembly Presidium President Kim Tu-bong, Minister of Defense Choe Yong-gon and Minister of Justice Lee Sung-yop. Soviet generals with extensive combat experience from World War II were sent to North Korea as the Soviet Advisory Group. They completed plans for attack by May and called for a skirmish to be initiated in the Ongjin Peninsula on the west coast of Korea. Kim suggested the invasion start in late June. Soviets thought the North Koreans needed more time to prepare, but as the rain season was about to begin in July, which could make North Korean advances harder, they ultimately accepted Kim's proposal. The North Koreans would then launch an attack to capture Seoul and encircle and destroy the ROK. The final stage would involve destroying South Korean government remnants and capturing the rest of South Korea, including the ports. On 7 June 1950, Kim called for a Korea-wide election on 5–8 August 1950 and a consultative conference in Haeju on 15–17 June. On 11 June, the North sent three diplomats to the South as a peace overture, which Rhee rejected outright. On 15 June, the invasion date was set to 25 June. On 21 June, Kim revised his war plan to involve a general attack across the 38th parallel, rather than a limited operation in Ongjin. Kim was concerned that South Korean agents had learned about the plans and that South Korean forces were strengthening their defenses. Stalin agreed to this change. On 24 June, division commanders received their invasion orders. The KPA planned defeating the South Koreans in twenty-two to twenty-seven days. While these preparations were underway in the North, there were clashes along the 38th parallel, especially at Kaesong and Ongjin, many initiated by the South. The ROK was being trained by the US Korean Military Advisory Group (KMAG). On the eve of the war, KMAG commander General William Lynn Roberts voiced utmost confidence in the ROK 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 US diplomat John Foster Dulles visited Korea on 18 June. Though some South Korean and US intelligence officers predicted an attack, similar predictions had been made before and nothing had happened. The Central Intelligence Agency noted the southward movement by the 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.
Course of the war
North Korean invasion (June 1950)
At 4:40 a.m. on 25 June 1950, the KPA crossed the 38th parallel behind artillery fire. The DPRK did not declare war before the invasion (called Operation Pokpung) and rushed to encircle and eventually capture Seoul, the capital of South Korea, from the ROK within a week. KPA forces swarmed South Korea and attacked all along the 38th parallel within an hour, and individual KPA units had advanced 3 to 5 kilometers into South Korean territory within the first three hours. The KPA had a combined arms force including tanks supported by heavy artillery supplied by the Soviet Union. The ROK had no tanks, anti-tank weapons, or heavy artillery. The South Koreans committed their forces in a piecemeal fashion, and these were routed in a few days. North Korea justified its assault with the claim ROK troops attacked first and that the KPA 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 the 17th Regiment had counterattacked at Haeju; some scholars argue the claimed counterattack was instead the instigating attack, and therefore that the South Koreans may have fired first. However, the report that contained the Haeju claim contained errors and outright falsehoods. On 27 June, Rhee evacuated Seoul with some of the government. On 28 June, the ROK blew up the Hangang Bridge across the Han River in an attempt to stop the KPA. The bridge was detonated while 4,000 refugees were crossing it and hundreds were killed. Destroying the bridge trapped many ROK units north of the river. In spite of such desperate measures, Seoul fell that same day. Some South Korean National Assemblymen remained in Seoul when it fell, and 48 subsequently pledged allegiance to the North. Within days of the invasion, masses of ROK soldiers, of dubious loyalty to the Syngman Rhee regime, were retreating southwards or defecting en masse to the northern side, the KPA. On 28 June, Rhee ordered the massacre of suspected political opponents in his own country. In five days, the ROK, which had 95,000 troops on 25 June, was down to less than 22,000 troops. In early July, when US forces arrived, what was left of the ROK was placed under US operational command of the UN Command.
UN Security Council resolutions
On 25 June 1950, the United Nations Security Council (UNSC) adopted Resolution 83 finding that the North Korean invasion of the Republic of Korea was a breach of the peace in violation of Chapter VII of the UN Charter. The Soviet Union, a veto-wielding power, had been boycotting the UN Security Council since January 1950 in protest of Taiwan's occupation of China's permanent seat. Due to this, the Soviet Union's representative was not present at the meeting and was unable to vote against the resolution.
On 27 June, the Security Council adopted Resolution 83 recommending its member states provide military assistance to South Korea to restore international peace, resulting in a coalition led by the United States. On 4 July, the Soviet Union's deputy foreign minister accused the US of starting an armed intervention on behalf of South Korea. The Soviet Union challenged the legitimacy of the war for several reasons. The ROK intelligence upon which UN Security Council Resolution 83 was based on came from US Intelligence; North Korea was not invited as a sitting temporary member of the UN, which violated Article 32 of the UN Charter; 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 UN Security Council, some legal scholars posited that deciding upon this type of action required the unanimous vote of all five permanent members. On 7 July, the Security Council adopted Resolution 84, which set up under the sponsorship of the British and French sides a Unified Command structure which was authorized to fly the blue flag of the UN but was not subject in any way to UN orders.
United States' response (July–August 1950)
As soon as word of the attack was received, Acheson informed Truman that the North Koreans had invaded the Republic of Korea. Truman and Acheson discussed a US response to the invasion and agreed the US was obligated to act, comparing the North Korean invasion with Adolf Hitler's aggressions in the 1930s, and the mistake of appeasement must not be repeated. The loose notion of a "police action" was used by President Harry S. Truman as a legal pretext for ordering US troops to Korea in June 1950 without first requesting congressional authority. US industries were mobilized to supply materials, labor, capital, production facilities, and other services necessary to support the military objectives of the Korean War. Truman later explained he believed fighting the invasion was essential to the containment of communism as outlined in the National Security Council Report 68 (NSC 68):
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 threats and aggression by stronger Communist neighbors. In August 1950, Truman and Acheson obtained the consent of Congress to appropriate $12 billion for military action, equivalent to $161 billion in 2025. Because of the extensive defense cuts and emphasis on building a nuclear bomber force, none of the services were able to make a robust response with conventional military strength. General Omar Bradley, Chairman of the Joint Chiefs of Staff, was faced with deploying a force that was a shadow of its World War II counterpart. Acting on Acheson's recommendation, Truman ordered MacArthur, the Supreme Commander for the Allied Powers in Japan, to transfer matériel to the South Korean military, while giving air cover to evacuation of US nationals. Truman disagreed with advisers who recommended unilateral bombing of the North Korean forces and ordered the US Seventh Fleet to protect Taiwan, whose government asked to fight in Korea. The US denied Taiwan's request for combat, lest it provoke retaliation from the PRC. Because the US had sent the Seventh Fleet to "neutralize" the Taiwan Strait, Chinese Premier Zhou Enlai criticized the UN and US initiatives as "armed aggression on Chinese territory". The US supported the Kuomintang in Burma in the hope these KMT forces would harass China from the southwest, thereby diverting Chinese resources from Korea.
Factors in US intervention
"Korea was a critical presence in American policy at the dawn of the Cold War. The Truman administration identified its stake in Korea in the same 'fifteen weeks' in which the containment doctrine and the Marshall Plan were hammered out." The Truman administration was worried a war in Korea could quickly escalate without American intervention. Diplomat John Foster Dulles stated: "To sit by while Korea is overrun by unprovoked armed attack would start a disastrous chain of events leading most probably to world war." While there was hesitance by some in the US government to get involved, considerations about Japan fed into the decision to engage on behalf of South Korea. After the fall of China to the communists, US experts saw Japan as the region's counterweight to the Soviet Union and China. While there was no US policy dealing with South Korea directly as a national interest, its proximity to Japan increased its importance. 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 US policy toward Japan." Another consideration was the Soviet reaction if the US intervened. The Truman administration was fearful the Korean War 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]". 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 start that would marginalize the UN and encourage communist aggression elsewhere. The UN Security Council approved the use of force to help the South Koreans. The Truman administration was uncertain whether the attack was a ploy by the Soviet Union, or just a test of US 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 US forces in Korea. The Truman administration believed it could intervene in Korea without undermining its commitments elsewhere.
==== US unpreparedness ==== The Truman administration was unprepared for the invasion. Korea was not included in the strategic Asian Defense Perimeter outlined by US Secretary of State Dean Acheson. Military strategists were more concerned with the security of Europe against the Soviet Union than that of East Asia. In postwar analysis of the unpreparedness of US forces deployed 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."
By 1950, US Secretary of Defense Louis A. Johnson had established a policy of faithfully following Truman's defense economization plans and aggressively attempted to implement it, even in the face of steadily increasing external threats. He consequently received much of the blame for the initial setbacks and widespread reports of ill-equipped and inadequately trained military forces in the war's early stages. As an initial response to the invasion, 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 US Navy no longer had the warships with which to carry out his request. Army officials, desperate for weaponry, recovered Sherman tanks and other equipment from Pacific War battlefields and reconditioned them for shipment to Korea. Army ordnance officials at Fort Knox pulled down M26 Pershing tanks from display pedestals around Fort Knox in order to equip the third company of the Army's hastily formed 70th Tank Battalion. Without adequate numbers of tactical fighter-bomber aircraft, the US Air Force took F-51 (P-51) propeller-driven aircraft out of storage or from existing Air National Guard squadrons and rushed them into front-line service. A shortage of spare parts and qualified maintenance personnel resulted in improvised repairs and overhauls. A Navy helicopter pilot aboard an active duty warship recalled fixing damaged rotor blades with masking tape in the absence of spares. US Army Reserve and Army National Guard infantry soldiers and new inductees (called to duty to fill out understrength infantry divisions) found themselves short of nearly everything needed to repel the North Korean forces: artillery, ammunition, heavy tanks, ground-support aircraft, even effective anti-tank weapons such as the M20 3.5-inch "Super Bazooka". Some Army combat units sent to Korea were supplied with worn-out, "red-lined" M1 rifles or carbines in immediate need of ordnance depot overhaul or repair. Only the Marine Corps, whose commanders had stored and maintained their World War II surplus inventories of equipment and weapons, proved ready for deployment, though they still were woefully understrength, as well as in need of suitable landing craft to practice amphibious operations (US Secretary of Defense Louis Johnson had transferred most of the remaining craft to the Navy and reserved them for use in training Army units).
=== The drive south and Pusan (July–September 1950) === The Battle of Osan, the first significant US engagement, involved the 540-soldier Task Force Smith, a small forward element of the 24th Infantry Division flown in from Japan. On 5 July 1950, Task Force Smith attacked the KPA at Osan but without weapons capable of destroying KPA tanks. The KPA defeated the US, with 180 American casualties. The KPA progressed southwards, pushing back US forces 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 or wounded and 2,962 captured, including its commander, Major General William F. Dean.
On 26 July 1950, US military aircraft strafed some refugees from Joo Gok Ri and Im Gae Ri. American soldiers inspected their belonging while the tired and hungry refugees sat and ate while seated on some railway tracks. "Shortly afterward, planes appeared overhead and strafed and bombed the villagers on the tracks killing 50–150 of them. Many of the survivors scrambled for cover into twin tunnels beneath the railroad tracks. There they crouched to avoid periodic gunfire that riddled the tunnel entrances for at least a day. This small arms fire killed another 60–300 villagers." This incident is known as the No Gun Ri massacre and was unknown to the American public until Associated Press journalists revealed what had occurred seventy years after the event, winning a Pulitzer Prize for their work. By August, the KPA steadily pushed back the ROK and the Eighth United States Army southwards. The impact of the Truman administration's defense budget cutbacks was keenly felt, as US troops fought costly rearguard actions. Facing a veteran and well-led KPA force, and lacking sufficient anti-tank weapons, artillery or armor, the Americans retreated and the KPA advanced down the Peninsula. By September, UN forces were hemmed into a corner of southeast Korea, near Pusan. This 230 kilometre (140 mile) perimeter enclosed about 10% of Korea, in a line defined by the Nakdong River. The KPA purged South Korea's intelligentsia by killing civil servants and intellectuals. On 20 August, MacArthur warned Kim Il-sung he would be held responsible for KPA atrocities. Kim's early successes led him to predict the war would finish by the end of August. Chinese leaders were more pessimistic. To counter a possible US deployment, Zhou secured a Soviet commitment to have the Soviet Union support Chinese forces with air cover, and he deployed 260,000 soldiers along the Korean border, under the command of Gao Gang. Zhou authorized a topographical survey of Korea and directed Lei Yingfu, Zhou's military adviser in Korea, to analyze the military situation. Lei concluded MacArthur would 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 PLA commanders to prepare for US naval activity in the Korea Strait. In the resulting Battle of Pusan Perimeter, UN forces withstood KPA attacks meant to capture the city at the Naktong Bulge, P'ohang-dong, and Taegu. The US Air Force interrupted KPA logistics with 40 daily ground support sorties, which destroyed 32 bridges, halting daytime road and rail traffic. KPA forces were forced to hide in tunnels by day and move only at night. To deny military equipment and supplies to the KPA, the USAF destroyed logistics depots, refineries, and harbors, while US Navy aircraft attacked transport hubs. Consequently, the overextended KPA could not be supplied throughout the south. On 27 August, aircraft from the 67th Fighter Squadron 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 composed of India and Sweden determine what the US should pay in compensation, but this was vetoed by the Soviet Union. Meanwhile, US garrisons in Japan continually dispatched soldiers and military supplies to reinforce defenders in the Pusan Perimeter. MacArthur went so far as to call for Japan's rearmament. Tank battalions deployed to Korea, from the port of San Francisco to the port of Pusan, the largest Korean port. By late August, the Pusan Perimeter had 500 medium tanks battle-ready. In early September 1950, UN forces outnumbered the KPA 180,000 to 100,000 soldiers.
Battle of Incheon (September 1950)
Against the rested and rearmed Pusan Perimeter defenders and their reinforcements, the KPA were undermanned and poorly supplied; unlike the UN, they lacked naval and air support. To relieve the Pusan Perimeter, MacArthur recommended an amphibious landing at Incheon, near Seoul, well over 160 kilometres (100 miles) behind the KPA lines. On 6 July, he ordered Major General Hobart R. Gay, commander of the US 1st Cavalry Division, to plan an 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, MacArthur began planning an Incheon landing, but the Pentagon opposed him. When authorized, he activated a combined US Army and Marine Corps, and ROK force. The X Corps, consisted of 40,000 troops of the 1st Marine Division, the 7th Infantry Division, and around 8,600 ROK soldiers. By 15 September, the amphibious force faced few KPA defenders at Incheon: military intelligence, psychological warfare, guerrilla reconnaissance, and protracted bombardment facilitated a light battle. However, the bombardment destroyed most of Incheon.
Breakout from the Pusan Perimeter
On 16 September, the Eighth Army began its breakout from the Pusan Perimeter. Task Force Lynch, 3rd Battalion, 7th Cavalry Regiment, and 70th Tank Battalion units advanced through 171 kilometres (106 miles) of KPA territory to join the 7th Infantry Division at Osan on 27 September. X Corps rapidly defeated the KPA defenders around Seoul, thus threatening to trap the main KPA force. On 18 September, Stalin dispatched General H. M. Zakharov to advise Kim to halt his offensive around the Pusan Perimeter, and redeploy his forces to defend Seoul. Chinese commanders were not briefed on North Korean troop numbers or operational plans. Zhou suggested the North Koreans should attempt to eliminate the UN 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 UN forces. US air raids caused heavy damage to the KPA, destroying most of its tanks and artillery. KPA troops in the south, instead of effectively withdrawing north, rapidly disintegrated, leaving Pyongyang vulnerable. During the retreat, only 25,000 to 30,000 KPA soldiers managed to reach the KPA lines. On 27 September, Stalin convened an emergency session of the Politburo, where he condemned the incompetence of the KPA command and held Soviet military advisers responsible for the defeat.
UN forces invade North Korea (September–October 1950)
On 27 September, MacArthur received secret National Security Council Memorandum 81/1 from Truman reminding him operations north of the 38th parallel was 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. The Joint Chiefs of Staff on 27 September sent MacArthur a comprehensive directive: it stated the primary goal was the destruction of the KPA, with the unification of the Peninsula under Rhee as a secondary objective "if possible"; the Joint Chiefs added this objective was dependent on whether the Chinese and Soviets would intervene, and was subject to changing conditions.
On 30 September, Zhou warned the US that China was prepared to intervene if the US crossed the 38th parallel. Zhou attempted to advise KPA commanders on how to conduct a general withdrawal by using the same tactics that allowed Chinese Communist forces to escape Nationalist encirclement campaigns in the 1930s, but KPA commanders did not use these tactics effectively. Bruce Cumings argues, however, that 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, the UNC had driven the KPA past the 38th parallel, and ROK forces pursued the KPA northwards. MacArthur demanded the KPA's unconditional surrender. On 7 October, with UN authorization, the UN Command forces followed the ROK forces northwards. The US Eighth Army drove up western Korea and captured Pyongyang on 19 October. On 20 October, the US 187th Airborne Regiment made their first of their two combat jumps during the war at Sunchon and Sukchon. The mission was to cut the road north to China, prevent North Korean leaders from escaping Pyongyang, and rescue US 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 80–161 kilometres (50–100 miles) of mountainous terrain. In addition to the 135,000 captured, the KPA had suffered some 200,000 soldiers killed or wounded, for a total of 335,000 casualties since the end of June 1950, and lost 313 tanks. A mere 25,000 KPA regulars retreated across the 38th parallel, as their military had collapsed. The UN forces on the peninsula numbered 229,722 combat troops (including 125,126 Americans and 82,786 South Koreans), 119,559 rear area troops, and 36,667 US Air Force personnel. MacArthur believed it necessary to extend the war into China to destroy depots supplying the North Korean effort. Truman disagreed and ordered caution at the Sino-Korean border.
China intervenes (October–December 1950)
On 15 October, Truman and MacArthur met at Wake Island. This was much publicized because of MacArthur's discourteous refusal to meet the president in the contiguous US. To Truman, MacArthur speculated there was little risk of Chinese intervention in Korea, and the PRC's opportunity for aiding the KPA had lapsed. He believed the PRC had 300,000 soldiers in Manchuria and 100,000 to 125,000 at the Yalu River. He 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 Soviet air force protection. Meanwhile, on 13 October, the Politburo decided China would intervene even without Soviet air support, basing its decision on a belief superior morale could defeat an enemy that had superior equipment.To that end, 200,000 Chinese People's Volunteer Army (PVA) troops crossed the Yalu into North Korea. UN aerial reconnaissance had difficulty sighting PVA units in the daytime, because their march and bivouac discipline minimized detection. The PVA marched "dark-to-dark" and aerial camouflage (concealing soldiers, pack animals, and equipment) was deployed. Meanwhile, daylight advance parties scouted for the next bivouac site. During daylight activity or marching, soldiers remained motionless if an aircraft appeared; PVA officers were under orders to shoot security violators. Such battlefield discipline allowed a three-division army to march the 460 kilometres (286 miles) from An-tung, Manchuria, to the combat zone in 19 days. Another division night-marched a circuitous mountain route, averaging 29 kilometres (18 miles) daily for 18 days.
After secretly crossing the Yalu River on 19 October, the PVA 13th Army Group launched the First Phase Offensive on 25 October, attacking advancing UN forces near the Sino-Korean border. This decision made solely by China changed the attitude of the Soviet Union. Twelve days after PVA troops entered the war, Stalin allowed the Soviet Air Forces to provide air cover and supported more aid to China. After inflicting heavy losses on 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. On 13 November, Mao appointed Zhou overall commander and coordinator of the war effort, with Peng Dehuai as field commander. On 25 November, on 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 inflicted heavy losses on the US 2nd Infantry Division on the UN forces' right flank. Believing they could not hold against the PVA, the Eighth Army began to retreat, crossing the 38th parallel in mid-December. In the east, on 27 November, the PVA 9th Army Group initiated the Battle of Chosin Reservoir. Here, the UN forces fared better: like the Eighth Army, the surprise attack forced X Corps to retreat from northeast Korea, but they were able to break out from the attempted encirclement by the PVA and execute a successful tactical withdrawal. X Corps established a defensive perimeter at the port city of Hungnam on 11 December and evacuated by December 24, to reinforce the depleted Eighth Army to the south. About 193 shiploads of UN 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 forces razed most of Hungnam, with particular attention to the port. In early December UN forces, including the British Army's 29th Infantry Brigade, evacuated Pyongyang along with refugees. Around 4.5 million North Koreans are estimated to have fled south or elsewhere abroad. On 16 December, Truman declared a national state of emergency with Proclamation No. 2914, 3 C.F.R. 99 (1953), which remained in force until September 1978. The next day, 17 December, Kim Il Sung was deprived of the right of command of KPA by China.
=== Bombing of North Korea (November 1950 – July 1953) === After Chinese intervention in November 1950, the United Nations Command (UNC) began an extensive bombing campaign against North Korea that lasted until the signing of the Armistice Agreement in July 1953. As Chinese forces compelled UN forces to retreat south and withdraw below the 38th parallel, the major North Korean cities would become targets of the UN Command. "When the United States began to lose after China intervened", the US bombing strategy moved progressively to "urban area bombardments". The US Air Force fighter-bombers began to conduct immense fire raids against entire towns, cities, and villages in North Korea. General Douglas MacArthur ordered the Air Force to "destroy every means of communication, every installation, every factory, city and village" north of Pyongyang. On 5 November 1950, twenty-one USAF B-29 Superfortress heavy bombers dropped 170 tons of incendiary bombs on the North Korean town of Kanggye, destroying 65% of the town's built-up area. On 8 November, seventy USAF B-29 bombers dropped more than 500 tons of incendiary bombs on Sinuiju, destroying 60% of the city's built-up area, including more than a square-mile area of buildings. By 28 November, "Bomber Command reported that 95% of the town of Manjopin's built-up area was destroyed", as well as for Hoeryong, 90%, Namsi, 90%, Chosan, 85%, Sakchu, 75%, Huichon, 75%, Koindong, 90%, and Uiju, 20%. In incendiary attacks on 3 and 5 January 1951, UN forces burned out 35% of Pyongyang, the capital city of North Korea and the country's largest city. By late 1951, the US Air Force judged that there were no more remaining targets worthy of using the "Tarzon", which was its largest conventional bomb at 12,000 pounds. On 11 July 1952, Operation Pressure Pump began with practically every operating unit in the Far East conducting an "all-out assault" on Pyongyang, which involved 1,254 air sorties by day and 54 B-29 assaults by night. "In the first attack, the US Air Force flew over 1,200 sorties, losing only three aircraft." On 29 August, an even heavier bombardment was conducted where more than 1,400 sorties were flown over Pyongyang. After the firebombing of Pyongyang, thirty other North Korean cities and industrial objectives were attacked by UN forces in Operation Pressure Pump. During these raids, UN forces used highly concentrated incendiary bombs followed up with delayed demolition explosives. In mid-May 1953, UN bombers attacked three dams: Toksan, Chasan, and Kuwonga. "The United States dropped 635,000 tons of bombs in Korea (not counting 32,557 tons of napalm), compared to 503,000 tons in the entire Pacific theater in World War II. Whereas sixty Japanese cities were destroyed to an average of 43 percent, estimates of the destruction of towns and cities in North Korea 'ranged from forty to ninety percent'; at least 50 percent of eighteen out of the North's twenty-two major cities were obliterated." A partial list of them includes Pyongyang, 75%, Chongjin, 65%, Hamhung, 80%, Hungnam, 75%, Sariwon, 90%, Sinanju, 100%, and Wonsan, 80%. US Army General Mark W. Clark saw heavy bombing of towns as a means of "undermining the morale of the people of North Korea and their ability to wage and support a war". The Far East Air Force (FEAF) "began incendiary raids against urban areas reminiscent of World War II, and MacArthur spoke of making the remaining territory held by the North Koreans a 'desert'".
Fighting around the 38th parallel (January–June 1951)
A ceasefire presented by the United Nations to the PRC, after the Battle of the Ch'ongch'on River on 11 December, was rejected by the PRC, which was convinced of the PVA's invincibility after its victory in that battle and the wider Second Phase Offensive. With Lieutenant General Matthew Ridgway assuming command of the Eighth Army on 26 December following the death of previous Eighth Army commander Walton Walker, the PVA and the KPA launched their Third Phase Offensive on New Year's Eve. Using night attacks in which UN fighting positions were encircled and assaulted by numerically superior troops, who had the element of surprise, the attacks were accompanied by loud trumpets and gongs, which facilitated tactical communication and disoriented the enemy. UN forces had no familiarity with this tactic, and some soldiers panicked, abandoning their weapons and retreating to the south. The offensive overwhelmed UN forces, allowing the PVA and KPA to capture Seoul for the second time on 4 January 1951. These setbacks prompted MacArthur to consider using nuclear weapons against the Chinese or North Korean interiors, intending radioactive fallout zones to interrupt the Chinese supply chains. However, upon the arrival of the charismatic General Ridgway, the esprit de corps of the bloodied Eighth Army revived.
