On May 11, 1995, over 170 signatory nations agreed to extend the Nuclear Nonproliferation Treaty (NPT) indefinitely. The NPT is an agreement signed by 189 countries to control the spread of nuclear weapons and nuclear technology based on the principles of disarmament, non-proliferation, and the use of nuclear technology for peaceful purposes. The treaty was opened for signature in 1968 with a provision for review conferences every five years. During the 1995 review conference in New York City, member countries decided to keep the treaty open indefinitely.
Learn more about the Nuclear Non-Proliferation Treaty from the United Nations.