List of parties to the Treaty on the Non-Proliferation of Nuclear Weapons

The list of parties to the Nuclear Non-Proliferation Treaty encompasses the states which have signed and ratified or acceded to the international agreement limiting the spread of nuclear weapons.

On 1 July 1968, the Nuclear Non-Proliferation Treaty (NPT) was opened for signature. The three depositary states were the Soviet Union (and later its successor state Russia), the United Kingdom, the United States; states wishing to become a party to the NPT must deposit their instruments of ratification, accession or succession with at least one of the depositary governments. The treaty came into force and closed for signature on 5 March 1970 with the deposit of ratification of the three depositary states and 40 others. Since then, states that did not sign the treaty may only accede to it.

The treaty recognizes five states as nuclear-weapon states: the United States, Russia, the United Kingdom, France, and China (also the five permanent members of the United Nations Security Council). China and France acceded to the treaty in 1992. Four other states are known or believed to possess nuclear weapons: India, Pakistan and North Korea have openly tested and declared that they possess nuclear weapons, while Israel has had a policy of opacity regarding its nuclear weapons program. India, Israel, and Pakistan have never signed the treaty, while North Korea was a party to the treaty but announced its withdrawal on 10 January 2003, which became effective ninety days later. However, there is disagreement among the parties to the treaty whether North Korea's withdrawal was in conformity with the terms of the treaty.

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