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.
Treaty on the Non-Proliferation of Nuclear Weapons
Four states—India, Israel, Pakistan, and South Sudan—have never signed the treaty. India and Pakistan have publicly disclosed their nuclear weapon programs, and Israel has a long-standing policy of deliberate ambiguity with regards to its nuclear program (see List of states with nuclear weapons).