Which U.S. president authorized the atomic bombings of Japan in 1945?

Harry S. Truman was the U.S. president who authorized the use of atomic bombs against Japan in 1945. He became president on April 12, 1945, after Franklin D. Roosevelt died.

Truman was informed about the Manhattan Project soon after taking office. The United States dropped Little Boy on Hiroshima on August 6 and Fat Man on Nagasaki on August 9. Truman publicly defended the attacks as a way to force Japan’s surrender and avoid a planned invasion of the Japanese home islands.

Roosevelt is sometimes named because he initiated the wartime atomic-bomb program, but he died before either weapon was used. General George Marshall was a senior military leader, not the president who made the authorization decision. Japan announced acceptance of the Allied terms on August 15.