25 June 1950
Korean War Begins
Just before dawn on a rainy Sunday morning units of the Army of the Democratic People’s Republic of Korea—North Korea—opened fire on South Korean forces stationed along the 38th parallel. The defenders were forced to retreat almost immediately, and the following day the South Korean government of Syngman Rhee evacuated the capital of Seoul. By the end of the month the North Koreans were deep within South Korean territory.

The United Nations Security Council responded to the invasion by passing a resolution demanding an immediate halt to the fighting and a withdrawal of North Korean forces to the 38th parallel. Ordinarily the Soviets would have been expected to veto such a resolution, but they were still boycotting U.N. proceedings over the issue of Chinese representation. Meanwhile President Truman authorized the overall U.S. commander in East Asia—General Douglas MacArthur, stationed in Japan—to send military assistance to South Korea. By the end of the month Truman had ordered MacArthur to dispatch U.S. combat troops to South Korea and to launch air and naval attacks against the North.

- United Nations Delay, Withdrawal, and Defense

- Telegram, dated June 24, 1950, from U.S. State Department to President Harry S. Truman regarding reports of North Korean forces invading the Republic of Korea

- Extract from telegram dated June 25, 1950, from John Foster Dulles and John M. Allison to Dean Acheson and Dean Rusk advocating the commitment of U.S. ground forces if the South Koreans fail to repulse North Korea

- Memorandum of conversation, dated June 25, 1950, by Philip C. Jessup summarizing a post-dinner meeting among the President and his advisors at Blair House. The conversation covered deployment of forces and materiel, as well as the foreign-policy implications of U.S. intervention in Korea

- Statement, dated June 26, 1950, from President Harry S. Truman announcing that it will be the policy of the United States to support the effort of the U.N. Security Council to put an end to the North Korean invasion of South Korea

- Memorandum of conversation, dated June 26, 1950, by Philip C. Jessup regarding a conversation at Blair House among President Truman and top U.S. military and state department officials in which Truman agreed that the U.S. should provide military support to South Korea, but only south of the 38th parallel

- Resolution dated June 27, 1950, from United Nations Security Council recommending that the members of the United Nations furnish assistance to the Republic of Korea in order to repel the attack and restore peace and security in Korea

- Statement, dated June 27, 1950, by President Harry S. Truman, announcing his order to send U.S. air and naval forces to help defend South Korea and explaining the rationale for his decision

The - North Korean Offensive, 25 June -- 15 September 1950