What did the acronym SCAP mean during the Allied occupation of Japan after its 1945 surrender?

During the Allied occupation of Japan, SCAP meant Supreme Commander for the Allied Powers.

SCAP was the title and headquarters structure used for the authority directing Japan’s occupation and reform after surrender. General Douglas MacArthur held the position, exercising broad authority over the Japanese government while formally operating under Allied arrangements.

The occupation began in late August 1945, with the first American forces landing before the formal surrender ceremony on September 2. SCAP supervised demilitarization, political reforms, economic changes, and the prosecution of major war criminals.

The acronym can be confusing because “SCAP” sometimes refers to MacArthur personally and sometimes to his headquarters or occupation administration. It did not mean a Japanese government department. The occupation ended in 1952 when the Treaty of San Francisco came into force, although some areas remained under separate American control for longer.