Nuclear weapon
Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated over two thousand times for testing and demonstration. Only a few nations possess such weapons or are suspected of seeking them. The only countries known to have detonated nuclear weapons—and acknowledge possessing them—are (chronologically by date of first test) the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, China, India, Pakistan, and North Korea. Israel is believed to possess nuclear weapons, though, in a policy of deliberate ambiguity, it does not acknowledge having them. Germany, Italy, Turkey, Belgium and the Netherlands are nuclear weapons sharing states. South Africa is the only country to have independently developed and then renounced and dismantled its nuclear weapons.
2010 NPT Review Conference
The Nuclear Nonproliferation Treaty (NPT), which entered into force in 1970, recognizes five countries as nuclear-weapon states (the United States, Russia, the United Kingdom, France, and China), who commit to pursue disarmament, and the right of other signatories to use nuclear technology for peaceful purposes, conditional upon their non-acquisition of nuclear weapons. Its ratification is nearly universal because it is adhered by 189 states, including five nuclear-weapon states, with the exception of Israel, India, and Pakistan. North Korea left the NPT and tested its first nuclear weapon in 2006.