The Korean War: Setting The Stage and Brief Overview

This article was originally published on the Department of Defense 50th Anniversary of the Korean War Commemoration website. Unfortunately that website is no longer accessible.

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The United States took its first real interest in Korea during World War II in the context of discussions over how to dismantle the Japanese Empire. At the Cairo Conference in November 1943, where the United States, Great Britain and China discussed wartime strategy and peace plans, the participants declared that “. . . in due course, Korea shall become free and independent.” President Franklin D. Roosevelt favored a trusteeship in Korea; whereby the United States, Great Britain, China and the Soviet Union would temporarily govern the country until Korea could manage its own affairs.

First meeting of the Joint American Soviet Commission in Seoul Korea First meeting of the Joint American-Soviet Commission in Seoul, Korea. The commission pledged cooperation to rehabilitate Korea economically and politically following Japanese rule of Korea which had ended in 1945. Jan. 16, 1946

In February 1945, at the Yalta Conference, Roosevelt raised the issue of Korea again, proposing a trusteeship involving the United States, China and the Soviet Union, which could last twenty to thirty years. Soviet Premier Josef Stalin replied that the “shorter the period the better.” With this general and vague agreement between Roosevelt and Stalin, discussion of the postwar future of Korea ended.

Roosevelt believed that a U.S.-Soviet trusteeship in Korea would provide the Soviet Union with an incentive for entering the war in the Pacific and encourage U.S.-Soviet cooperation. But after Roosevelt’s death in April 1945, in the context of tension over the Soviet occupation policies in Eastern Europe, the tone of American-Soviet relations declined dramatically. As a consequence, the American position towards Korea began to change under the leadership of President Harry S. Truman.

The unconditional Japanese surrender on Aug. 14, 1945, came shortly after the atomic bombings of Hiroshima and Nagasaki. With the sudden Japanese collapse came the threat that the Soviets, advancing into Manchuria and Korea, could quickly gain control of the entire Korean peninsula. In response, Army planners in the War Department and the State Department proposed a plan that would divide the peninsula in half, leaving the Soviets to occupy Korea north of the 38th parallel and an American occupation force south of the line. The Soviets agreed and moved quickly to occupy major cities north of the 38th parallel. The U.S. military arrived at Inchon on Sept. 8, and began occupying the southern half of the peninsula. The simultaneous establishment of two zones led to the division that remains to this day.

In 1946, Stalin pronounced that international peace was impossible “under the present capitalist development of the world economy.” The next year, George F. Kennan, a former counselor of the U.S. Embassy in Moscow and Director of the Department of State’s Policy Planning Staff, recommended that the proper response to the Soviet threat was “a long-term, patient but firm and vigilant containment of Russian expansive tendencies.” To that end, Truman announced his approach to foreign policy saying, “I believe that it must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.”

At the Moscow Conference in December 1945, the United States, Soviet Union and Great Britain proposed trusteeship of Korea and created the Joint Soviet-American Commission. This commission sought to establish a provisional Korean democratic government. When its cooperative endeavors for Korean independence failed, the United States made one final attempt to resolve the Korean question, but the Soviets rejected that proposal. The U.S. then presented the issue before the United Nations (U.N.) on Sept. 14, 1947.

Soon after, in the spring of 1948, the U.N. General Assembly resolved that the Korean people would elect one national assembly for the whole country. South Koreans participated in a U.N.-supervised election in May 1948 that selected members of the National Assembly. That assembly ratified the country’s constitution July 17, 1948. The Republic of Korea (ROK) was formally established on Aug. 14, 1948. Dr. Syngman Rhee, an outspoken anti-communist and the State Department’s choice to head an independent Korea, became the first president. Soviet authorities prohibited an election in the North and refused to permit the U.N. Election Commission to enter North Korea. The northern half of Korea held separate elections in the fall of 1948, establishing the Democratic People’s Republic of Korea and inaugurating Kim Il Sung as its new president.

With the creation of the Republic of Korea, the U.S. Military Government ended its control. The 50,000 American occupation troops completed a gradual withdrawal by June 1949. Only the Korean Military Advisory Group (KMAG), numbering approximately 500 American officers and enlisted men, remained to continue training Korean security forces. The existence of a communist insurgency coupled with the desire to prevent President Rhee from attempting to unify the peninsula by force, led the United States to structure the ROK Army as a constabulary force, a lightly-armed force designed to maintain internal order. In contrast, the Soviet Union outfitted the North Korean Army with heavy tanks and long-range artillery.

Also in 1949, the Chinese communists won the civil war in China. This success emboldened Kim Il Sung to make several trips to Moscow to persuade Stalin to support reunification of Korea by force. Not until Kim convinced the Soviet dictator that a North Korean invasion would quickly subdue the South before the United States could intervene did Stalin give his approval. The Soviets provided essential logistical support and technical advisors for the invasion force. In the spring of 1950, Secretary of State Dean Acheson defined America’s strategic defense perimeter in Asia, which excluded the Korean peninsula. This confirmed Stalin and Kim’s assessments of the strategic situation.

In June 1950, the United States was not prepared to wage war. Public sentiment against a large standing military establishment and the desire to produce consumer goods forced the government to reduce defense expenditures after World War II. America’s policy of containment of communism and its increasing dependence on the atomic bomb and strategic air power caused a significant reduction in the strength of the Army, Navy and Marine Corps. As a result, there were few trained units available for immediate commitment in Korea when the North Koreans invaded.

On June 25, 1950, the North Korean Army attacked across the 38th parallel to unify the peninsula. That action caused President Truman to commit U.S. Forces, unprepared as they were, to the defense of South Korea. The United Nations Security Council simultaneously called upon member states to do likewise. For the first time, the United Nations authorized the establishment of a multinational force, flying the U.N. banner, to repel aggression.

When North Korean forces invaded the Republic of Korea, the United States, considering it an act of aggression, requested the United Nations take immediate action. On June 25, 1950 (New York time) the U.N. Security Council responded quickly by passing a resolution which called for immediate cessation of hostilities and withdrawal of all North Korean forces to the 38th parallel. (The Soviet member was absent because of a boycott since January 1950, over the issue of seating communist China’s representative in the United Nations). On June 27, after the Republic of Korea appealed to the United Nations for assistance, the Security Council passed another resolution recommending that United Nations members furnish assistance to South Korea as needed to “repel the armed attack and to restore international peace and security to the area.” Fifty-three member nations approved the Security Council’s recommendations.

Under a resolution introduced by Great Britain on July 7, the United Nations asked the United States to lead the Unified Command to put down the North Korean aggression. The United States accepted the responsibility and Truman appointed General of the Army Douglas MacArthur as commanding general. Twenty other countries (19 members and Italy, a nonmember at the time) contributed to the war effort.

The initial North Korean offensive drove the defenders into the southeast corner of the peninsula. There the Pusan Perimeter was established and, reinforced by American divisions, held through bitter battles. That stout defense made possible a brilliantly-conceived amphibious assault at Inchon, which enveloped the overextended North Korean Army and recaptured the capital city of Seoul. United Nations forces then advanced north to the Yalu River on the border between Korea and China, to try to reunify Korea.

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In November 1950, concluding that the U.N. forces posed a threat to China, Mao Tse-tung ordered the massive intervention of the Chinese communist forces, which profoundly altered the nature of the war. Overwhelmed by vastly superior numbers and ill equipped for combat in sub-zero weather, U.N. forces withdrew to a line well south of Seoul, regrouped, and by March 1951, fought their way back to the 38th parallel. In April and May, the Chinese forces launched successive major offensives against U.N. troops.

In June 1951, with battle lines once again set along the pre-invasion boundary, Jacob Malik, the Soviet delegate to the United Nations, suggested negotiations to terminate armed hostilities. During the two years of peace talks, opposing forces remained locked in bloody, inconclusive combat, at a tremendous loss of life. Finally, on July 27, 1953, representatives for the United States and North Korea (also representing China) signed the Military Armistice Agreement. The government of South Korea refused to sign because a permanently divided Korea was unacceptable. In the absence of a political settlement, that agreement continues to regulate the de facto boundary between the two Koreas. Today, there is still no official peace on the peninsula.

Koreans South vote during the first democratic election held on May 10 1948 Koreans (South) vote during the first democratic election held on May 10, 1948.
Jacob A. Malik Jacob A. Malik, the Soviet representative on the United Nations Security Council, raises his hand to cast the only dissenting vote to the resolution calling on the Chinese communists to withdraw troops from Korea. December 1950.


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