I CONFERRED Sunday evening with the Secretaries of State and Defense, their senior advisers, and the Joint Chiefs of Staff about the situation in the Far East created by unprovoked aggression against the Republic of Korea.
The Government of the United States is pleased with the speed and determination with which the United Nations Security Council acted to order a withdrawal of the invading forces to positions north of the 38th parallel. In accordance with the resolution of the Security Council, the United States will vigorously support the effort of the Council to terminate this serious breach of the peace.
Our concern over the lawless action taken by the forces from North Korea, and our sympathy and support for the people of Korea in this situation, are being demonstrated by the cooperative action of American personnel in Korea, as well as by steps taken to expedite and augment assistance of the type being furnished under the Mutual Defense Assistance Program.
Those responsible for this act of aggression must realize how seriously the Government of the United States views such threats to the peace of the world. Willful disregard of the obligation to keep the peace cannot be tolerated by nations that support the United Nations Charter.
Harry S Truman, Statement by the President on the Violation of the 38th Parallel in Korea. Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/230840