The Nuclear Nonproliferation Treaty (NPT) at a Glance

Contact: Daryl Kimball, Executive Director, (202) 463-8270 x107

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which entered into force in March 1970, seeks to inhibit the spread of nuclear weapons. Its 190 (191 with North Korea*) states parties are classified into two categories: nuclear-weapon states (NWS)—consisting of the United States, Russia, China, France, and the United Kingdom—and non-nuclear-weapon states (NNWS). Under the treaty, the five NWS commit to pursuing general and complete disarmament, while the NNWS agree to forgo developing or acquiring nuclear weapons.

With its near-universal membership, the NPT has the widest adherence to any arms control agreement, with only South Sudan, India, Israel, and Pakistan remaining outside the treaty. In order to accede to the treaty, these states must do so as NNWS, since the treaty restricts NWS status to nations that "manufactured and exploded a nuclear weapon or other nuclear explosive devices prior to 1 January 1967." For India, Israel, and Pakistan, all known to possess or suspected of having nuclear weapons, joining the treaty as NNWS would require that they dismantle their nuclear weapons and place their nuclear materials under international safeguards. South Africa followed this path to accession in 1991.

Select Treaty Articles

Under Articles I and II of the treaty, the NWS agree not to help NNWS develop or acquire nuclear weapons, and the NNWS permanently forswear the pursuit of such weapons. To verify these commitments and ensure that nuclear materials are not being diverted for weapons purposes, Article III tasks the International Atomic Energy Agency (IAEA) with the inspection of the non-nuclear-weapon states' nuclear facilities. In addition, Article III establishes safeguards for the transfer of fissionable materials between NWS and NNWS.

Article IV acknowledges the "inalienable right" of states-parties to research, develop, and use nuclear energy for non-weapons purposes. It also supports the "fullest possible exchange" of such nuclear-related information and technology between NWS and NNWS.

Article V, now effectively obsolete, permits NNWS access to NWS research and development on the benefits of nuclear explosions conducted for peaceful purposes. As the perceived utility of peaceful nuclear explosions has diminished over time, the relevance of this clause has lost much of its practical value. It is now moot due to the restriction on all nuclear explosions mandated by the Comprehensive Test Ban Treaty—to which all five NWS are signatories.

Article VI commits states-parties to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control." Acknowledging the necessity of intermediate steps in the process of nuclear disarmament, Article VII allows for the establishment of regional nuclear-weapon-free-zones.

Article VIII requires a complex and lengthy process to amend the treaty, effectively blocking any changes absent clear consensus. Article X establishes the terms by which a state may withdraw from the treaty, requiring three months' advance notice should "extraordinary events" jeopardize its supreme national interests.

The remainder of the treaty deals with its administration, providing for a review conference every five years and a decision after 25 years on whether the treaty should be extended. The 1995 review conference extended the treaty indefinitely and enhanced the review process by mandating that the five-year review conferences review past implementations and address ways to strengthen the treaty. Review conferences were held in 2000, 2005, 2010, and 2015 respectively. The 2020 conference was postponed due to the COVID-19 pandemic and held in August 2022 at the United Nations. 

For more on the history of the NPT and its review conferences, see the Timeline of the Nuclear Nonproliferation Treaty (NPT). The treaty text can be found here.


*North Korea announced on January 10, 2003, that it was withdrawing from the treaty, effective the next day. Although Article X of the NPT requires that a country give three months' notice in advance of withdrawing, North Korea argued that it satisfied this requirement because it originally announced its decision to withdraw on March 12, 1993, and suspended the decision one day before it was to become legally binding. There is not yet a definitive legal opinion as to whether North Korea is still a party to the NPT.