USS Iowa (BB-61) 1948, as part of the post World War II drawdown of the armed forces, "Iowa" was deactivated at San Francisco, and then formally decommissioned into the United States Navy reserve fleets on 24 March 1949. In 1950, North Korea invaded South Korea, prompting the United Nations to authorize military intervention. President Harry S. Truman ordered US forces stationed in Japan to transfer to South Korea. Truman also sent US based troops, tanks, fighter and bomber aircraft, and a strong naval force to the area to support South Korea. As part of the naval mobilization, "Iowa" was reactivated on 14 July
United Nations Command members providing military forces and other assistance to South Korea "make such forces and other assistance available to a unified command under the United States of America". President Syngman Rhee of the Republic of Korea assigned operational command of ROK ground, sea, and air forces to General MacArthur as Commander-in-Chief UN Command (CINCUNC) in a letter (the "Pusan Letter") of July 15, 1950: On August 29, 1950, the British Commonwealth's 27th Infantry Brigade arrived at Busan to join UNC ground forces, which until then included only ROK and U.S. forces. The 27th Brigade moved into the Naktong River line west