SCAP identified Douglas MacArthur’s Allied occupation headquarters in postwar Japan.
The abbreviation stood for Supreme Commander for the Allied Powers, the title held by MacArthur during the occupation. It also commonly referred to the headquarters and administrative apparatus operating under his authority.
SCAP began functioning after the Japanese surrender and directed the demilitarization and reconstruction of Japan. Its responsibilities included dismantling the wartime military system, supervising political reforms, and overseeing the prosecution of suspected war criminals.
Although MacArthur was the leading Allied official in Japan, SCAP was not simply an American civil government. The occupation formally represented the Allied powers, with policy shaped through the Allied Council for Japan and the Far Eastern Commission. In practice, however, the United States exercised predominant influence over the occupation’s administration.