The Treaty on the Prohibition of Nuclear Weapons (TPNW), negotiated by more than 130 states, is a good faith effort to meet their responsibility as signatories of the nuclear Nonproliferation Treaty (NPT) to pursue effective measures on disarmament. The prohibition treaty further reinforces the commitments of these states against the use, threat of use, development, production, manufacture, acquisition, possession, stockpiling, transfer, stationing, or installation of nuclear weapons. It reinforces states' commitments to the NPT and the Comprehensive Test Ban Treaty (CTBT). Although the prohibition treaty by itself will not eliminate any nuclear weapons, the treaty can help to further delegitimize nuclear weapons and strengthen the legal and political norm against their use.
On October 24, 2020, the the 50th state (Honduras) delivered its instrument of ratification, triggering the treaty's entry into force 90 days later, on January 22, 2021. As of December 2021, 86 states have signed the treaty and 58 have ratified it.
The treaty has a 24-paragraph preamble acknowledging the catastrophic humanitarian consequences of nuclear weapons use and the value of existing international disarmament agreements including the NPT, the CTBT, and nuclear-weapon-free-zone agreements, as well as the “right” of states-parties to peaceful uses of nuclear energy.
Prohibitions (Article 1)
States-parties are prohibited to use, threaten to use, develop, produce, manufacture, acquire, possess, stockpile, transfer, station, or install nuclear weapons or assist with any prohibited activities.
Declarations (Article 2)
A state-party must declare, when joining the treaty, whether it has eliminated a previous nuclear weapons program, currently has nuclear weapons, or holds another country's nuclear weapons on its territory. If a state has another country’s nuclear weapons on its territory when it signs the treaty, it must remove them. If it has its own nuclear weapons, it must eliminate them.
Safeguards (Article 3)
Non-nuclear-weapon states are required to have, at a minimum, a comprehensive safeguards agreement with the International Atomic Energy Agency (IAEA) “without prejudice” to any future additional agreements.
Nuclear-weapon states accession (Article 4)
There are two ways for a nuclear-weapon state to accede to the treaty and eliminate its nuclear weapons: It can join the treaty and then destroy its nuclear weapons or destroy its nuclear weapons and then join the treaty. States that “destroy and join” must cooperate with a “competent international authority” designated by the treaty to verify dismantlement. States that “join and destroy” must immediately remove nuclear weapons from operational status and submit a time-bound plan for their destruction within 60 days of joining the treaty.
The treaty does not specify which “competent international authority” would be suited to verify irreversible disarmament of a nuclear-armed state that decides to join the treaty, but the treaty allows for an appropriate authority to be designated at a later date. The treaty requires any current or former nuclear-weapon state that seeks to join the prohibition treaty to conclude a safeguards agreement with the IAEA to verify that nuclear materials are not diverted from peaceful to weapons purposes.
Positive obligations (Articles 6 and 7)
The treaty obligates states-parties to provide victim assistance and environmental remediation to those affected by nuclear weapon use and testing.
Meetings of states-parties, signature, ratification and entry into force (Articles 8, 13, 14, and 15)
Biennial meetings of states-parties will address implementation and other measures. Review conferences will be held every six years. The treaty, opened for signature on September 20, 2017, entered into force 90 days after the 50th state ratified it (on Jan. 22, 2021).
The initiative to negotiate a "legally binding instrument" to prohibit nuclear weapons is the result of a years-long process that grew out of a renewed recognition of the catastrophic humanitarian consequences of nuclear weapons use, the rising risk of accidental or intentional nuclear use, and a growing sense of frustration that key nuclear disarmament commitments made by the nuclear-weapon states were not being fulfilled.
The 2010 NPT Review Conference unanimously "expresse[d] its deep concern at the continued risk for humanity represented by the possibility that these weapons could be used and the catastrophic humanitarian consequences that would result from the use of nuclear weapons."
These concerns motivated a group of states—including Norway, Mexico, and Austria—to organize a series of three conferences in 2013 and 2014 on the humanitarian consequences of nuclear weapon use.
Following the conclusion of the 2015 NPT Review Conference, these and other states agreed to set up an open-ended working group in 2016 on advancing multilateral disarmament negotiations. The working group led to the formulation of a resolution in the UN General Assembly to start negotiations in 2017 on a treaty prohibiting nuclear weapons. The resolution passed the UN General Assembly First Committee by a vote of 123-38 with 16 abstentions in October 2016 and was subsequently adopted by the General Assembly as a whole.
The first negotiating session was held at the UN in New York on March 27-31, 2017, with some 130 governments, and dozens of civil society organizations, participating. The president of the negotiations, Ambassador Elayne Whyte Gomez, compiled states' expressed opinions from the first round of negotiations into a draft convention on the prohibition of nuclear weapons issued on May 22 in Geneva. The second and final round of negotiations took place on June 15-July 7 in New York, with participants adopting the Treaty on the Prohibition of Nuclear Weapons by a vote of 122-1-1. The Netherlands voted against adoption, and Singapore abstained.
Reactions from the Nuclear-Armed States
Nuclear-weapon states and many NATO members have opposed the initiative from the beginning. Although the United States and the United Kingdom participated in the 2014 Conference on the Humanitarian Impacts of Nuclear Weapons in Vienna, leaders from Washington and the other nuclear-weapon states boycotted the working group sessions and the 2017 treaty negotiations.
These states contend that the treaty will distract attention from other disarmament and nonproliferation initiatives. They have expressed concern that the nuclear prohibition treaty could undermine the NPT and the extensive safeguard provisions included therein by giving states the option to "forum shop," or choose between the two treaties.
Arguments for the Treaty from Proponent States
Supporters of the nuclear prohibition treaty argue that it will close a "legal gap" that exists regarding nuclear weapons, which are not expressly outlawed by the NPT even though their use would be contrary to the rules of international law applicable in armed conflict. They argue that the prohibition treaty initiative reinforces the NPT and its Article VI requirement for nuclear disarmament and that it can reduce the salience of nuclear weapons and help prompt more urgent action to reduce nuclear risk and promote disarmament.
May 3-28: The final document of the 2010 Review Conference for the nuclear Nonproliferation Treaty (NPT) acknowledges the humanitarian consequences of nuclear weapons use.
March 4-5: The first conference on the humanitarian impact of nuclear weapons use takes place in Oslo, Norway.
February 13-14: The second conference on the humanitarian consequences of nuclear weapons use takes place in Nayarit, Mexico.
December 8-9: The final conference on the humanitarian consequences of nuclear weapons use takes place in Vienna, Austria.
December 9: 127 states endorse the Humanitarian Pledge, calling on all NPT states parties to renew their commitment to Article VI of the NPT and to take interim steps to reduce the risk of nuclear use.
October 29: The UN General Assembly First Committee votes 135-12 with 33 abstentions on a resolution to create an Open Ended Working Group to take forward multilateral nuclear disarmament negotiations.
February 22-26: The first working group to advance multilateral nuclear disarmament negotiations meets in Geneva, Switzerland.
May 2-4 and 9-13: The second working group to advance multilateral nuclear disarmament negotiations meets in Geneva, Switzerland.
August 16-19: The third working group to advance multilateral nuclear disarmament negotiations meets in Geneva, Switzerland, approving a final report by a vote of 68-22 with 13 abstentions.
October 27: The First Committee adopts a resolution to begin negotiations in 2017 on a nuclear prohibition treaty by a vote of 123-38 with 16 abstentions.
December 23: The General Assembly approves the resolution to begin negotiations on a nuclear prohibition treaty adopted by the First Committee by a vote of 113-35 and 13 abstentions.
March 27-31: The first round of negotiations on a treaty prohibiting nuclear weapons takes place at the United Nations in New York.
May 22: President Elayne Whyte Gómez presents the first draft text of the treaty at the United Nations in Geneva.
June 15-July 7: The second round of negotiations on a treaty to prohibit nuclear weapons takes place at the United Nations in New York.
July 7: The treaty prohibiting nuclear weapons is adopted by a vote of 122-1-1. The Netherlands voted against the treaty, and Singapore abstained.
September 20: The TPNW opens for signature in New York. Fifty states signed the treaty, and three additional states both signed and ratified it by the day's end.
October 23-24: Jamaica, Nauru, and Honduras become the 48th, 49th, and 50th states to deliver their ratification documents, which triggers the treaty's entry into force 90 days later.
January 22: The treaty entered into force.
March 22-24: First meeting of States Parties, Vienna, Austria
See here for a full list of signatories and states-parties.