SCAP identified the Allied occupation authority in Japan after its 1945 surrender.
SCAP stands for Supreme Commander for the Allied Powers, the title held by General Douglas MacArthur during the U.S.-led occupation of Japan. The position was created at the start of the occupation on August 14, 1945, just before Japan’s surrender announcement became public.
In practice, “SCAP” could refer both to MacArthur’s position and to the occupation headquarters and administrative apparatus operating under his authority. In Japan, the headquarters was also commonly called GHQ, meaning General Headquarters. That overlap explains why historical sources sometimes use SCAP and GHQ in closely related ways.
SCAP issued directives to Japan’s government, supervised demilitarization, and helped guide postwar political and economic reforms. MacArthur remained in the role until April 1951. The occupation formally ended when the San Francisco Peace Treaty took effect on April 28, 1952, although some U.S. territories in Japan remained under separate American administration.