Nuclear weapons debate
After the bombings of Hiroshima and Nagasaki, the world’s nuclear weapons stockpiles grew, and nuclear weapons have been detonated on over two thousand occasions for testing and demonstration purposes. Countries known to have detonated nuclear weapons—and that acknowledge possessing such weapons—are (chronologically): the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, the People's Republic of China, India, Pakistan, and North Korea.
Nuclear proliferation
Efforts to conclude an international agreement to limit the spread of nuclear weapons did not begin until the early 1960s, after four nations (the United States, the Soviet Union, the United Kingdom and France) had acquired nuclear weapons (see List of states with nuclear weapons for more information). Although these efforts stalled in the early 1960s, they renewed once again in 1964, after China detonated a nuclear weapon. In 1968, governments represented at the Eighteen Nation Disarmament Committee (ENDC) finished negotiations on the text of the NPT. In June 1968, the U.N. General Assembly endorsed the NPT with General Assembly Resolution 2373 (XXII), and in July 1968, the NPT opened for signature in Washington, DC, London and Moscow. The NPT entered into force in March 1970.