Walton Walker backed South Korea, and China allied with the Soviet Union in what was to become the first military action of the Cold War. Shortly after 75,000 North Korean troops with tanks invaded South Korea on June 25, 1950, American air and sea forces were ordered by President Harry S. Truman to give South Korean troops support. The U.S. Eighth Army was ordered to intervene and drive the invaders back across the 38th parallel, the border between the two countries. With only four lightly equipped and poorly trained divisions, Walker began landing troops on the southeast side of the Korean peninsula
United States Air Force In South Korea 80 miles north of the 38th parallel. Naval air power also attacked transportation choke points. The North Korean forces were already strung out over the peninsula, and the destruction caused by American bombers prevented needed supplies from reaching North Korean forces in the south. With control of the air obtained, General MacArthur's invasion of Inchon on 15 September 1950 suddenly reversed the fortunes of the UN forces in Korea. In the south, the Eighth U.S. Army, made up of U.S., ROK, and British forces, counterattacked the next day and United Nations forces in the Pusan Perimeter began to push north