The United States first celebrated V-J Day on August 14, 1945, after Japan announced its surrender.
President Harry S. Truman announced the news from the White House on August 14 in U.S. time. Because of the international date line and time differences, it was already August 15 in Japan, where Emperor Hirohito’s recorded surrender broadcast was heard.
The date distinction explains why American and Japanese accounts may give different dates for V-J Day. August 14 is the traditional U.S. date for the public announcement, while August 15 is often called V-J Day in Japan and other countries.
The surrender was not yet formally documented on August 14. Japanese and Allied representatives signed the Japanese Instrument of Surrender on September 2, 1945, aboard USS Missouri in Tokyo Bay.