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.^[1] However, there is disagreement among the parties to the treaty whether North Korea's withdrawal was in conformity with the terms of the treaty.^[2]

The NPT remains the most widely subscribed to nuclear arms control treaty in history.^[3] As of February 2015, 190 states are recognized as parties to the treaty, excluding North Korea which withdrew. The State of Palestine is the most recent state to have joined, having submitted its instrument of succession on 10 February 2015. In addition, the Republic of China (Taiwan), which is currently only recognized by 11 UN member states, ratified the treaty prior to the United Nations General Assembly's vote to transfer China's seat to the People's Republic of China (PRC) in 1971; Taiwan has accepted comprehensive International Atomic Energy Agency (IAEA) safeguards and the measures of the Additional Protocol to verify that its nuclear program is entirely peaceful.^[4] Four UN member states have never signed the treaty: India, Israel, Pakistan, and South Sudan. The Cook Islands and Niue, two associated states of New Zealand which have had their "full treaty-making capacity" recognised by United Nations Secretariat,^[5] are not parties to the treaty but consider themselves bound by its provisions by virtue of their administration by New Zealand when the latter ratified the NPT.^[6]