Safeguards to Prevent Nuclear Proliferation

Most countries participate in international initiatives designed to limit the proliferation of nuclear weapons. The international safeguards system has since 1970 successfully prevented the diversion of fissile materials into weapons.

Hiroshima, Nagasaki, and Subsequent Weapons Testing

Two atomic bombs made from uranium-235 and plutonium-239 were dropped on Hiroshima and Nagasaki respectively early in August 1945. The atmospheric testing of some 545 nuclear weapons continued up to 1963.