Which Allied document did Japan accept in announcing its surrender in August 1945?

Japan accepted the Potsdam Declaration when it announced its surrender in August 1945.

The declaration was issued on July 26, 1945, by the United States, the United Kingdom, and China. It demanded Japan's unconditional surrender and outlined broad conditions for the country's postwar future, including the limitation of Japanese sovereignty and the disarmament of its military.

The Soviet Union was not an original signatory because it was still neutral toward Japan when the declaration was released. After entering the war against Japan in August, the Soviet government also subscribed to the declaration. Japan formally accepted its terms in the imperial message broadcast on August 15.

The Potsdam Declaration should not be confused with the Cairo Declaration of 1943. Cairo addressed Allied goals concerning territories taken by Japan, while Potsdam presented the immediate surrender demand. The formal written surrender on September 2 implemented the acceptance announced in August.