US Entry into the Korean War: Origins, Impact, and Lessons

ABSTRACT This article describes the reasons for the outbreak of the Korean War and US entry into the conflict. At the end of World War II, the United States and the Soviet Union divided Korea into two zones of military occupation. Cold War discord between the two nations blocked agreement to end the division, resulting in formation of two Korean governments each bent on reunification. Soviet Premier Joseph Stalin reluctantly supported the Democratic People’s Republic of Korea’s invasion of the Republic of Korea on 25 June 1950 after Kim Il Sung persuaded him that victory would be quick and easy. President Harry S. Truman immediately saw the attack as the first step in a Soviet plan to use military means to achieve global dominance, but he initially ordered limited US military intervention, maintaining a prewar policy of qualified containment in Korea. When the Republic of Korea failed to halt the invasion, he sent US ground forces to prevent the Communist conquest of the peninsula. Truman wanted to avoid another world war and did not consider use of atomic weapons until China intervened. This article concludes that resumption of the Korean War is unlikely because of the US treaty commitment to defend the Republic of Korea and the weakness of the Democratic People’s Republic of Korea.