Treaty on the Prohibition of Nuclear Weapons

On July 7, 2017, history was made when the majority of United Nations member states adopted a ban on nuclear weapons, the Treaty on the Prohibition of Nuclear Weapons (TPNW). 72 years after nuclear weapons were first tested. On January 22, 2021, the treaty entered into force. Nuclear weapons were then, as the last weapon of mass destruction, banned under international law.

A ban on nuclear weapons

In 2017, negotiations on a ban on nuclear weapons started, which took place at the UN headquarters in New York for 4 weeks. Close to 130 nuclear-weapon-free states participated in the negotiations. The nuclear weapon states did not participate and the Netherlands was the only NATO state to participate.

122 states voted in favor of the treaty, which was adopted on July 7, 2017. For the treaty to enter into force, 50 states were required to ratify it. On September 20, 2017, the treaty opened for signatures and on January 22, 2021, the agreement entered into force.

What is prohibited?

The Treaty on the Prohibition of Nuclear Weapons is a comprehensive agreement that prohibits all forms of nuclear weapons activities. That includes a ban on developing, testing, producing, acquiring, possessing, stockpiling, using or threatening to use nuclear weapons, or supporting other countries’ nuclear weapons programs. The ban is anchored in and strengthens international humanitarian law.


The nine countries that have nuclear weapons are investing huge sums to renew and develop their nuclear arsenals. At the same time, five of them; France, China, Russia, the United Kingdom and the United States, are part of the Non-Proliferation Treaty and have thus committed to disarm their nuclear weapons. Something they have not done on a sufficient scale. The other four nuclear weapons states, India, Israel, North Korea and Pakistan, are not part of any disarmament agreements at all.

Nuclear weapons have always been a technical and complicated issue, the humanitarian consequences of nuclear weapons received little space during the Non-Proliferation Treaty conferences and at other meetings where nuclear weapons were discussed. It was not until 2010 that humanitarian consequences of nuclear weapons were first noted into the Review Conference of the Non-Proliferation Treaty Final Document.

In 2013, the former Norwegian government formulated what has come to be known as the Humanitarian Initiative. The initiative puts the humanitarian consequences of nuclear weapon use at the center and was adopted as a resolution during the First Committee of the UN General Assembly in 2015.

Three conferences

Within the initiative, three intergovernmental conferences were organized to highlight the humanitarian consequences of nuclear weapon use.

Oslo, Norway

The first intergovernmental conference was held in Oslo, Norway in March 2013 and 132 states participated. The common conclusion was that it is unlikely that any state or international body could address the immediate humanitarian emergency caused by a nuclear weapon detonation in an adequate manner and provide sufficient assistance to those affected. And it might not be possible to establish such capacities, even if it were attempted. As this fact became clear, a number of states recognized their joint responsibility to act to prevent both the accidental and intentional use of these weapons of mass destruction.

From this a new conversation was born. A conversation between countries that do not possess nuclear weapons, about the unreasonableness of some countries being allowed to expose other countries’ populations to such risks. Frustration at the reluctance of the nuclear-weapon states to disarm was added to this realization and an initiative grew and took shape.

Nayarit, Mexico

The second intergovernmental conference was held in Nayarit, Mexico in February 2014. Over 140 States participated and the Conference was another step forward, offering a new platform to strengthen the humanitarian case and to continue to engage non-nuclear weapon states in a constructive dialogue on a ban on and elimination of nuclear weapons.

Vienna, Austria

In December 2014, the third intergovernmental conference on the Humanitarian Consequences of Nuclear Weapons was held in Vienna, Austria. This conference brought together 155 states, including the United States and United Kingdom. At the end of the conference, the government of Austria launched the Austrian Pledge, which during the 2015 Non-Proliferation Treaty Review Conference was renamed the Humanitarian pledge.

A forth conference was held in Vienna, Austria, in June 2022. This conference was followed by the First meeting of State Parties for the Treaty on the Prohibition of Nuclear Weapons (TPNW).

UN General Assembly

As of December 2015, 121 states have formally joined the Humanitarian pledge and during the 2015 UN General Assembly First Committee, the pledge was adopted as a resolution with the support of 139 states.

During the First Committee of the UN General Assembly in 2015, several resolutions were put on the table that dealt with different ways of dealing with the disarmament of nuclear weapons and ways forward. The nuclear-weapon-free states had their agenda ready, they want to ban nuclear weapons – with or without the nuclear-weapon states. In 2016, a resolution was passed to begin negotiations on a ban on nuclear weapons. The following year, in 2017, the Treaty on the Prohibition of Nuclear Weapons was negotiated.


A common criticism of the nuclear weapons ban is that the nuclear weapon states are not included – what difference does it make? Nuclear weapons are the last weapon of mass destruction now banned under international law. The international community has banned other weapons because of their unacceptable humanitarian consequences, such as cluster munitions, biological and chemical weapons, and anti-personnel mines.

Although not all states have signed up to all agreements, the effects have been clear: after bans follow changes in norms, increased pressure on disarmament and, in many cases, concrete disarmament. Prohibiting nuclear weapons is also a matter of states assuming their responsibility to develop international law and to implement the disarmament requirements of the UN Charter and the Non-Proliferation Treaty (NPT).

Critics have argued that this ban is toothless because the nuclear weapon states have not been involved. But the ban is far from toothless. The nuclear weapon states are affected to the highest degree and have already been affected by the discussion about what happens if nuclear weapons are actually used.

Now the threshold to use nuclear weapons is being raised. Norms change. It is about additional opportunities to influence banks, pension companies, companies and more, and everything is aimed at making it more difficult to have and produce nuclear weapons. The world’s states and large companies are also affected by standards, and they will do so regardless of whether they are part of the agreement or not.

Sources and more information

Treaty on the prohibition of nuclear weapons, United Nations Office for Disarmament Affairs
United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards their Total Elimination, United Nations Office for Disarmament Affairs
Treaty on the Prohibition of Nuclear Weapons, United Nations General Assembly
The Treaty, International Campaign to Abolish Nuclear Weapons, ICAN


Swedish Physicians Against Nuclear Weapons

Last updated
12 January, 2023