What is the Non-Proliferation Treaty?

The Treaty on the Non-Proliferation of Nuclear Weapons, or Non-Proliferation Treaty (NPT) for short, is sometimes confused with the newer Treaty on the Prohibition of Nuclear Weapons (TPNW). Here’s what you need to know about the two treaties.

1968 Non-Proliferation Treaty (NPT)

Negotiated in the 1960s and in force since 1970, the Non-Proliferation Treaty’s main aim is to stop the spread of nuclear weapons to more countries. It has been largely successful in doing that: only a few countries have acquired a nuclear capability since its negotiation.

But the treaty also includes an obligation to “pursue negotiations” for nuclear disarmament. In that respect, it has been less successful, as nuclear-armed countries continue to spend tens of billions of dollars every year enhancing their nuclear arsenals, with no plans to disarm.

A third element of the NPT is its promotion of the use of nuclear energy for “peaceful purposes”, such as electricity generation, subject to international safeguards.

The NPT does not establish an outright ban on nuclear weapons for all of the countries that have joined it, nor does it include any detailed provisions stipulating how and when disarmament should take place.

Most of the world’s countries have joined the NPT and are therefore legally required to abide by it. This includes five of the nine countries that possess nuclear weapons: China, France, Russia, the United Kingdom and the United States. Their obligations under the treaty are different from the obligations of other countries.

Many of the NPT’s parties believe that these five countries are failing to fulfil their obligations under the treaty, as they still possess thousands of nuclear weapons between them and are not engaging in disarmament negotiations.

Three countries with nuclear weapons have never joined the NPT: India, Israel and Pakistan. North Korea, which also has nuclear weapons, withdrew from the treaty in 2003.

2017 Treaty on the Prohibition of Nuclear Weapons (TPNW)

Full text of TPNW

As the NPT does not ban nuclear weapons outright and it is not being faithfully implemented by its nuclear-armed parties, a majority of the world’s countries decided to negotiate the Treaty on the Prohibition of Nuclear Weapons (TPNW) in 2017 as a complementary measure.

Following its ratification by 50 countries, it entered into force in 2021, filling a major gap in international law. Prior to its entry into force, nuclear weapons were the only weapons of mass destruction not subject to a comprehensive treaty-based prohibition.

The TPNW does three main things: 1) it prohibits a wide range of activities relating to nuclear weapons; 2) it establishes a framework for getting rid of nuclear weapon stockpiles verifiably; and 3) it seeks to address the harm caused by the use and testing of nuclear weapons globally.

To date, around half of the world’s countries have joined the TPNW, either as parties or signatories. More are likely to join it in the coming years.

All nine countries that possess nuclear weapons have expressed their opposition to the treaty, as they are not yet willing to disarm. But it can still influence their behaviour through its normative force and in practical ways, such as prompting financial institutions to divest from nuclear-weapon-producing companies.

Nuclear-armed countries are free to join the TPNW at any time. Upon doing so, they will need to remove their nuclear weapons from operational status immediately and destroy them in accordance with a negotiated, time-bound plan.

Alternatively, countries that currently have nuclear weapons can opt to destroy them before joining, in which case the elimination of their weapons would need to be verified by an international authority.

Adoption of the TPNW at the United Nations in 2017. Photo: Clare Conboy / ICAN

Comparing the two treaties

The Non-Proliferation Treaty (1968):

Prohibits five of the nine nuclear-armed states – China, France, Russia, the UK, and the US – from transferring their nuclear weapons to anyone else or assisting other states to acquire nuclear weapons.

Prohibits all other parties from manufacturing or otherwise acquiring nuclear weapons.

Facilitates the exchange of equipment, materials, and scientific and technological information for the “peaceful uses of nuclear energy”, subject to safeguards agreements.

Requires all parties to “pursue negotiations in good faith on effective measures relating to the cessation of the nuclear arms race and to nuclear disarmament” (without specifying what those measures must be or imposing any timelines).

The Treaty on the Prohibition of Nuclear Weapons (2017):

Prohibits a wide range of activities relating to nuclear weapons, including their use, threatened use, development, testing, manufacture and possession, as well as assistance with any of those activities.

Establishes a legal framework for the verified, time-bound elimination of nuclear-weapon programmes and the removal of foreign-owned nuclear weapons from the territory of its parties.

Reinforces and extends the NPT requirement for safeguards to ensure that nuclear materials and technology are not used for weapons.

Establishes a legal framework for assisting victims of the use and testing of nuclear weapons, and for the remediation of contaminated environments.

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