Truman's public announcement in Washington, D.C., 16 hours after the attack, was Tokyo's first knowledge of what had really happened to Hiroshima: "Sixteen hours ago an American airplane dropped one bomb on Hiroshima. It is an atomic bomb. We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. If they do not now accept our terms they may expect a rain of ruin from the air the like of which has never been seen on this earth."

Type	Nuclear weapon
Place of origin	United States
Production history
Designer	Los Alamos Laboratory
Produced	1945
No. built	1
Specifications
Weight	9,700 pounds (4,400 kg)
Length	10 feet (3.0 m)
Diameter	28 inches (71 cm)
Filling	Uranium-235
Filling weight	140 lb (64 kg)
Blast yield	15 kilotons of TNT (63 TJ; 0.7 g mass equivalent)