However, on August 6, 1945, the US dropped an atomic bomb over Hiroshima, killing over 70,000 people. This was the first nuclear attack in history. On August 9 the Soviet Union declared war on Japan and invaded Manchukuo and other territories, and Nagasaki was struck by a second atomic bomb, killing around 40,000 people. The surrender of Japan was communicated to the Allies on August 14 and broadcast by Emperor Hirohito on national radio the following day.