Which U.S. president announced the formal V-J Day after Japan signed its surrender?

Harry S. Truman announced the formal V-J Day after Japan signed its surrender.

Truman became U.S. president in April 1945 after Franklin D. Roosevelt died. He was president during the final campaigns against Japan, the atomic bombings of Hiroshima and Nagasaki, the Soviet entry into the Pacific War, and Japan's surrender. After the formal signing on 2 September 1945, Truman designated that date as the official V-J Day in the United States.

The term V-J means “Victory over Japan.” It was modeled on V-E Day, or Victory in Europe Day, which marked Nazi Germany's surrender earlier in 1945. Different countries and communities used different dates for V-J observances. Japan's public announcement occurred on 15 August, while the United States announced the surrender on 14 August because of time-zone differences; the formal signing occurred on 2 September.