What Allied ultimatum did Japan accept before the formal surrender ceremony?

Japan accepted the Potsdam Declaration before the formal surrender ceremony.

The United States, the United Kingdom, and China issued the declaration on 26 July 1945 during the Potsdam Conference. It demanded Japan’s unconditional surrender and warned of “prompt and utter destruction” if Japan refused. The Soviet Union joined the declaration after entering the war against Japan, although it was not an original signatory.

Japan’s government accepted the declaration in August 1945 after intense debate. The acceptance was communicated to the Allies and announced publicly through Hirohito’s recorded radio address on 15 August. The Japanese Instrument of Surrender later formalized that acceptance on 2 September.

The Potsdam Declaration is distinct from the surrender instrument. The declaration was an Allied demand and statement of terms; the instrument was the document Japan signed to capitulate. The Cairo Declaration, issued in 1943, also addressed Japan’s territorial future but was not the document accepted immediately before the surrender.