Korean War Begins

The Korean War began in June 1950, when North Korean forces crossed the 38th parallel and invaded South Korea. It grew from a civil conflict on a divided peninsula into an international war involving the United States, China, the Soviet Union, and a United Nations coalition. It ended in 1953 with an armistice rather than a peace treaty, leaving Korea divided to this day and hardening Cold War alignments in East Asia.

The roots of the war lay in the end of World War II. Korea had been a Japanese colony since 1910, and in 1945 American and Soviet forces occupied the south and north respectively, with the 38th parallel as a dividing line. Attempts to reunify the country under agreed terms failed. By 1948 two rival governments had emerged: the Republic of Korea in the south, led by Syngman Rhee, and the Democratic People's Republic of Korea in the north, led by Kim Il Sung. Each claimed to be the legitimate government of all Korea, and border clashes and insurgencies were common before 1950.

The invasion began in late June 1950. Kim Il Sung had sought support from Joseph Stalin and Mao Zedong, and historians generally agree that Stalin gave a reluctant approval and supplied equipment and advisers. North Korean forces quickly captured Seoul and pushed the South Korean and American defenders into a small perimeter around Pusan. The UN Security Council, which the Soviet Union was boycotting at the time, authorized a military response, and the United States led a multinational force under General Douglas MacArthur. His amphibious landing at Inchon in September turned the tide, and UN forces advanced deep into North Korea toward the Chinese border.

China then intervened. Beijing viewed the approach of UN troops to the Yalu River as a threat, and in late 1950 large numbers of Chinese "volunteers" entered the war and drove UN forces back south of Seoul. The front stabilized near the 38th parallel in 1951, and the conflict became a bloody stalemate marked by trench warfare, heavy air campaigns, and prolonged negotiations. MacArthur was dismissed in April 1951 after publicly disagreeing with President Truman over limiting the war.

An armistice was signed in July 1953, establishing a demilitarized zone near the original line. Estimates of the dead vary widely, but total casualties, military and civilian, likely numbered in the millions, with Korean civilians suffering enormously. The war led to a lasting US military presence in South Korea, a mutual defense treaty, and a heavily militarized border. It also accelerated American rearmament and the spread of Cold War alliances in Asia. No peace treaty has ever been concluded, so the two Koreas remain technically at war.