Just three days after the United Nations Security Council voted to provide military assistance to South Korea, President Harry S. Truman orders U.S. armed forces to assist in defending that nation from invading North Korean armies. Truman's dramatic step marked the official entry of the United States into the Korean War.
On June 25, 1950, military forces from communist North Korea invaded South Korea. South Korean forces and the small number of U.S. troops stationed in the nation reeled under the surprise attack. On June 27, the United States asked the Security Council in the United Nations to pass a resolution calling on member states of the United Nations to assist South Korea. With the Soviets boycotting the meeting for other reasons, the resolution passed. Three days later, President Truman ordered U.S. ground forces into South Korea and the troops entered South Korea that same day. At the same time, Truman ordered the U.S. Air Force to bomb military targets in North Korea and directed the U.S. Navy to blockade the North Korean coast.
Truman's action signaled the beginning of official and large-scale U.S. participation in the Korean War. Over the next three years, the United States provided at least half of the U.N. ground forces in Korea and the vast majority of the air and sea forces used in the conflict against North Korea and, later, against communist China, which entered the war on the side of North Korea in late 1950. Nearly 55,000 Americans were killed in the war and over 100,000 were wounded. Cost estimates for the war ranged as high as $20 billion. In July 1953, an armistice was signed that ended the fighting and left Korea a divided nation.