SCAP identified the Allied authority that administered occupied Japan after its 1945 surrender.
SCAP stands for Supreme Commander for the Allied Powers, the title used for General Douglas MacArthur and the organization operating under him during the occupation of Japan. The occupation began in late August 1945, and MacArthur established his headquarters in Tokyo.
SCAP issued directives to the Japanese government rather than replacing every Japanese administrative institution directly. The organization supervised demilitarization, political reform, economic measures, and the creation of a new postwar framework. Japan’s existing bureaucracy continued functioning under Allied direction.
The acronym is sometimes confused with GHQ, meaning General Headquarters, which was the headquarters structure through which SCAP operated. It is also distinct from SWPA, the Southwest Pacific Area command that MacArthur led during the war. SCAP remained central to the occupation until the Treaty of San Francisco took effect in 1952.