The Treaty on the Prohibition of Nuclear Weapons: From New York Negotiations to Implementation

On 23 December 2016, the United Nations General Assembly adopted Resolution 71/258, deciding to convene a negotiating conference the following year to develop a legally binding instrument to prohibit nuclear weapons, leading towards their total elimination. The resolution followed discussions in that year's open-ended working group in Geneva. It identified the catastrophic humanitarian consequences of nuclear explosions, the risks of accidents or miscalculation, and slow progress on disarmament as reasons for action.

The Assembly called for discussions open to all Member States, with international organizations and civil society representatives also participating. At the same time, the resolution reaffirmed the importance of the Treaty on the Non-Proliferation of Nuclear Weapons, considering that new legal measures should complement and strengthen the existing regime. It also acknowledged that other legal and practical measures would be needed to achieve genuinely verifiable and irreversible elimination.

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The organizational meeting took place at United Nations Headquarters in New York on 16 February 2017. Costa Rican diplomat Elayne Whyte Gómez was elected President of the conference. Substantive negotiations were held in two sessions, from 27 to 31 March and from 15 June to 7 July, with 29 plenary meetings in total. Countries including Austria, New Zealand and South Africa served as Vice-Presidents, and the conference also established specific arrangements for participation by non-governmental organizations.

On 7 July, at its 28th meeting, the conference adopted the treaty text by 122 votes in favour, one against and one abstention. It subsequently adopted its report to the General Assembly by consensus. The number of votes in favour of the text cannot simply be equated with the number of ratifying countries or States Parties: each country still had to complete its own procedures for expressing consent to be bound.

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Article 1 prohibits developing, testing, producing, possessing, transferring, using or threatening to use nuclear weapons. It also covers assistance with prohibited activities and allowing foreign nuclear weapons to be stationed on a country's territory. Article 2 requires States Parties to declare their nuclear-weapon status. Articles 3 and 4 address safeguards, verification for states that have already relinquished nuclear weapons, and time-bound destruction after accession while possessing nuclear weapons as distinct cases.

The treaty establishes procedures for different circumstances and requires domestic legislation, administrative measures and necessary penal sanctions to support implementation.

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The treaty also requires assistance, including medical care, rehabilitation and psychological support, for people under a State Party's jurisdiction who have been affected by the use or testing of nuclear weapons, as well as action to remediate contaminated areas. International cooperation can supplement the capacities of affected states. States Parties that have used or tested nuclear weapons also bear corresponding responsibilities to provide assistance.

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The United Nations Secretary-General's depositary notification of 9 August 2017 confirmed that the treaty would open for signature at United Nations Headquarters in New York on 20 September. It also explained that heads of state, heads of government and foreign ministers could sign by virtue of their offices without separate instruments of full powers, while other representatives needed appropriate authorization. The date of adoption of the text was thus clearly distinct from the date it opened for signature.

Entry into force depended on more than reaching a certain number of signatures: it was to occur 90 days after the deposit of the fiftieth instrument of ratification, acceptance, approval or accession. The depositary notification of 26 October 2020 recorded that this condition had been met on 24 October. The treaty therefore entered into force on 22 January 2021.

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The first Meeting of States Parties was held in Vienna from 21 to 23 June 2022, chaired by Alexander Kmentt of Austria. Forty-nine States Parties attended, together with observers from other states and organizations. The meeting adopted the Vienna Action Plan and set a maximum ten-year deadline for the destruction of nuclear weapons under Article 4, with a procedure for conditional extension. It set a maximum period of 90 days for the removal of foreign nuclear weapons from a host state. Where genuinely necessary, the destruction deadline could be extended by a decision, by up to five additional years. The meeting thus established both target deadlines and a procedure for handling exceptions.

The meeting also decided to establish a Scientific Advisory Group. For victim assistance and environmental remediation, the action plan called for points of contact, needs assessments and national plans, as well as a study of the feasibility of an international trust fund.

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