On August 29, 1949 the Soviet Union successfully tested its first atomic bomb. The weapon was similar in design and explosive power to the United States' "Fat Man" plutonium bomb detonated over Nagasaki, Japan four years earlier. The Soviets did not make any public statement about this development, but American intelligence agencies discovered evidence that was consistent with an explosion. It was formally announced on September 23 by United States President Harry S. Truman and confirmed the next day by the Soviet government. In only four years the U.S. monopoly on atomic weapons was over, and the country began an arms race with the Soviet Union.

Throughout the Cold War the U.S. government promoted the idea that nuclear war was survivable for those who took the proper precautions and had knowledge of how to protect themselves. The 1951 film Duck and Cover was created by the Federal Civil Defense Administration to teach school children how to protect themselves from a nuclear blast. The film's main character Bert the Turtle shows children how to hide under their desks and cover their heads to protect themselves from the effects of a bomb. You can view the film .