The Nuclear Arms Race, 1939-1981
American participation in a nuclear arms race began as a direct result of a letter sent to President Franklin D. Roosevelt in August 1939 by eminent physicist Albert Einstein. In it, Einstein warned the president that the Nazis were preparing to develop nuclear weapons. Roosevelt responded by initiating action that ultimately led, in August 1942, to the establishment of the Manhattan Project, the U.S. program to develop the atomic bomb.
The fact that the Germans were unable to build nuclear weapons before they were defeated in World War II did not bring the Manhattan Project to an end. Instead, Roosevelt had decided in September 1944 that the atomic bomb, if it were successfully developed, would be used against Japan, which continued to fight after Germany had surrendered.
The moral problem of using the atomic bomb against civilian targets like Hiroshima and Nagasaki apparently did not bother Roosevelt or his successor, Harry S. Truman. World War II had helped to anesthetize American moral sensibilities concerning the killing of civilians. In fact, more people were killed by the firebombing of Tokyo in one night than died in either Hiroshima or Nagasaki. Moreover, Truman and many others argued afterward that use of the atomic bombs saved the lives of hundreds of thousands