What was the 1945 Allied ultimatum that demanded Japan's surrender before the final ceremonies?

The Potsdam Declaration was the 1945 Allied ultimatum that demanded Japan's surrender.

The United States, United Kingdom, and China issued the declaration on July 26, 1945, during the Potsdam Conference. It called on Japan to surrender its armed forces and warned of “prompt and utter destruction” if Japan refused. The Soviet Union did not initially sign because it was not yet at war with Japan, but later agreed to adhere to the declaration.

Japan did not immediately accept the ultimatum. The United States dropped atomic bombs on Hiroshima on August 6 and Nagasaki on August 9, while the Soviet Union declared war and invaded Manchuria. Japan then announced its acceptance of the Allied terms in August.

The Potsdam Declaration is distinct from the Cairo Declaration of 1943, which described Allied goals for territories taken from Japan. The later Instrument of Surrender formally recorded Japan's acceptance.