Treaty on the Non-Proliferation of Nuclear Weapons

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is an international treaty, opened for signature on 1 July 1968 and in force since 5 March 1970, that commits states without nuclear weapons not to acquire them, commits the five states that had them to pursue nuclear disarmament, and guarantees all parties access to nuclear energy for peaceful purposes.^{1 • 2} With 191 states parties, it is considered the cornerstone of the global nuclear non-proliferation regime.³

Origins and negotiation

From the beginning of the nuclear age, and the use of nuclear weapons at Hiroshima and Nagasaki in 1945, it was apparent that states developing nuclear capabilities could divert technology and materials to weapons purposes.⁶ In the early Cold War, President John F. Kennedy had warned of a world in which 15, 20, or 25 nations might possess nuclear weapons.⁸ Nuclear technology was also no longer pursued only by governments but by private companies, and the science of exploding and fusing atoms had entered public literature through academic journals.⁹

Negotiations began in earnest in 1965 at the Geneva disarmament conference.⁹ A revised draft submitted in January 1968 by the United States and the Soviet Union, as co-chairs of the Eighteen-Nation Disarmament Committee, added the disarmament article, Article VI, whose final phrasing was agreed on 11 March 1968.¹⁰ China and France did not participate in the negotiations but had acquired nuclear weapons before the negotiation was completed.¹¹ States began signing in 1968, and the treaty went into force in 1970.¹¹

Structure of the treaty

The treaty rests on interlocking obligations described as three pillars: non-proliferation, disarmament, and peaceful uses.¹²

• Articles I and II prevent the spread of nuclear weapons: nuclear-weapon states undertake not to transfer them or help any non-nuclear state acquire them, and non-nuclear states undertake not to acquire them.¹³
• Article III provides international safeguards, implemented by the International Atomic Energy Agency (IAEA), to assure that peaceful nuclear activities of non-nuclear states are not diverted to weapons. A comprehensive safeguards agreement combined with an Additional Protocol represents the current verification standard under Article III(1).^{13 • 14}
• Article IV enshrines the inalienable right of all parties to develop research, production, and use of nuclear energy for peaceful purposes without discrimination.¹⁵
• Article VI commits each party to pursue negotiations in good faith on effective measures relating to nuclear disarmament.¹³
• Article X allows withdrawal in the event of extraordinary events and provided for a conference 25 years after entry into force to decide whether the treaty should continue indefinitely or be extended for a fixed period.^{6 • 12}

In joining the NPT, non-nuclear-armed states agreed never to acquire nuclear weapons, while the five nuclear-armed states recognized by the treaty, the United States, Russia, the United Kingdom, France, and China, committed to making progress toward complete disarmament.¹⁶

Extension and the review process

At the NPT Review and Extension Conference in May 1995, states parties agreed, without a vote, on the treaty's indefinite extension and decided that review conferences should continue every five years.⁶ The 1995 conference also adopted a package of principles and objectives on non-proliferation and disarmament intended to hold states parties, particularly the nuclear-weapon states, accountable to their commitments.⁵ Article VIII.3 required a first review conference five years after entry into force, held in Geneva in 1975, and the parties endorsed continuing such meetings.¹⁷

The review process has often been contentious. Since the treaty entered into force in 1970, half of its first 10 review conferences ended without agreement on a final document.¹⁸ Review conferences operate by consensus, so any party can block agreement, which limits their ability even to express common opinions.¹⁹

The 2026 Review Conference

The 11th Review Conference met at United Nations headquarters in New York from 27 April to 22 May 2026, chaired by Vietnam's UN Ambassador Do Hung Viet.⁷ It ended without a consensus final document, the third consecutive failure after 2015 and 2022.³ The president said no single state blocked consensus; he had withheld the draft document because consensus was absent, and he identified as a very important reason a provision stating that Iran "can never seek, develop or acquire any nuclear weapons."³ At the opening, the United States and Iran clashed over Iran's election as one of 34 vice presidents of the conference, a candidacy of the Non-Aligned Movement.²⁰ The 2022 conference had failed after Russia blocked agreement over references to its February 2022 invasion of Ukraine and its occupation of the Zaporizhzhia nuclear power plant.³

States parties agreed that the next review conference will be held in 2031, with the next preparatory meeting in 2028.⁷

Record and current pressures

The treaty is widely judged a partial success. It did not ultimately prevent nuclear proliferation, but in the context of the Cold War arms race it set a precedent for cooperation between nuclear and non-nuclear states to prevent proliferation.⁹ Warnings that dozens of states would acquire nuclear weapons have not come to pass, and the global tally of nuclear weapons fell from more than 60,000 in 1986 to less than 10,000 by the early 2020s, almost all held by the United States or Russia.¹⁶

Pressures on the regime have grown. North Korea withdrew in 2003 and has since built an arsenal estimated by the IAEA at several dozen warheads.¹² India and Pakistan, which have not signed, tested nuclear weapons in 1998; Israel, also a non-signatory, is widely believed to possess them.² The expiration of the New START treaty in February 2026 without a successor left the world without any legally binding, verifiable agreement between nuclear-weapon states on the size or deployment of nuclear arsenals.²¹ Analysts have also identified structural weaknesses: the vague terms of Article VI have enabled nuclear-weapon states to justify limited disarmament progress, and the consensus rule at review conferences repeatedly produces deadlock.^{22 • 19}

The NPT coexists with the Treaty on the Prohibition of Nuclear Weapons (TPNW), adopted in 2017 and in force since 2021, which requires the complete elimination of nuclear weapons; the five NPT nuclear-weapon states oppose the TPNW, arguing it fails to address the key obstacles to disarmament.^{12 • 16}

References

1. NPT Briefing Book 2026, James Martin Center for Nonproliferation Studies
2. These countries have nuclear weapons or are believed to have them, AP News
3. Conference at UN to review nuclear nonproliferation treaty fails to reach agreement, AP News
4. Timeline of the Nuclear Nonproliferation Treaty (NPT), Arms Control Association
5. The NPT at 50: A Historical Timeline, Arms Control Association
6. Background, NPT 2026, United Nations
7. 2026 NPT Review Conference Stymied by Disputes, Arms Control Association
8. A landmark nuclear arms treaty shows its age, Axios
9. Milestones in the History of U.S. Foreign Relations: The Nuclear Nonproliferation Treaty, Office of the Historian, U.S. Department of State
10. Debating Disarmament: Interpreting Article VI of the NPT, Nonproliferation Review
11. The Nuclear Nonproliferation Treaty: History and Current Problems, Arms Control Association
12. Pillars of nuclear non-proliferation treaty are being undermined, Le Monde
13. Non-Proliferation Treaty, U.S. Department of State (archived)
14. NPT/CONF.2026/PC.II/WP.11, United Nations Digital Library
15. NPT, Nuclear Threat Initiative
16. She's Spent a Decade Fighting to Ban Nuclear Weapons, TIME
17. The 1999 NPT PrepCom, Nonproliferation Review
18. Review of the Nuclear Non-Proliferation Treaty: A Practitioner's Perspective, Journal for Peace and Nuclear Disarmament
19. How the impasse over Iran sank the NPT Review Conference, Bulletin of the Atomic Scientists
20. US and Iran clash over Tehran's nuclear program as review of atomic treaty begins at UN, AP News
21. NPT/CONF.2026/WP.32, Ministry of Foreign Affairs of Japan
22. The Nuclear Non-Proliferation Treaty's Gordian Knot, International & Comparative Law Quarterly

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026

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