Before America even entered WWII, work started on the "Manhattan Project," a secret project (unknown even to then-Vice President Harry Truman) to develop an atomic bomb. This project began after scientists discovered Hitler's work to split the uranium atom. By 1945, when the atomic bomb was first successfully tested, Germany had surrendered to the Allies in Europe, but Japan’s Emperor was still refusing to surrender. With the prospect of a million US casualties if the U.S. invaded Japan, Harry Truman decided to drop the bombs after a final effort to convince the Japanese to surrender. Dropping the bomb would also send a clear message to the Soviet Union. Days after dropping the bomb on Hiroshima, America dropped another nuclear bomb on Nagasaki. Combined, the bombs brought about the immediate deaths of 120,000 people with tens of thousands of more to follow. Debate still exists as to whether the US should have dropped the bombs. As a result of the bombs, V-J Day was declared, ending the war with Japan, but people continued to die because of radiation illnesses, and citizens of both cities had a higher risk of cancer for the rest of their lives.