The Treaty on the Prohibition of Nuclear Weapons (the “Treaty“) entered into force on 22 January 2021. The Treaty is the first treaty to ban nuclear weapons, and has received support to date from 88 States.


The Treaty was adopted by the United Nations General Assembly on 7 July 2017 and has been open for signature to all States since 20 September 2017 (Article 13). The Treaty complements the existing international legal framework regulating nuclear weapons, which includes the Treaty on the Non-Proliferation of Nuclear Weapons and the Comprehensive Nuclear-Test-Ban Treaty.

Article 15(1) of the Treaty provides that it will enter into force 90 days following the deposit of the 50th instrument of ratification, acceptance, approval or accession. The Treaty therefore came into force on 22 January 2021, 90 days following the deposit of Honduras’ instrument of ratification. There are currently 86 Signatory States and 52 State Parties, including Benin and Cambodia, who ratified the Treaty after Honduras, and Austria, South Africa, Thailand, Indonesia, Kazakhstan and Mexico. States that have not adopted the Treaty include the United Kingdom, the United States, Russia, China, France, India, Pakistan, North Korea and Israel.

Selected provisions of the Treaty


Article 1 of the Treaty prohibits the development, testing, production, manufacturing, acquisition, possession or stockpiling of nuclear weapons or other nuclear explosive devices (referred to collectively as “Nuclear Weapons“). It also prohibits the transfer of Nuclear Weapons, receipt of such transfers, the threat or use of Nuclear Weapons, providing assistance to anyone engaging in any activities prohibited under the Treaty or seeking or receiving such assistance. The stationing, installation or deployment of Nuclear Weapons in a State Party’s own territory or at any place under its jurisdiction and control is also strictly prohibited.

Elimination of nuclear weapons

The Treaty also contains provisions which govern the elimination of nuclear weapons. Notably, Article 4(2) states that “each State Party that owns, possesses or controls nuclear weapons or other nuclear explosive devices shall immediately remove them from operational status, and destroy them as soon as possible“. State Parties are not required to have commenced that process prior to ratification.

Victim assistance and environmental remediation

Article 6(1) provides that each State Party shall “adequately provide age- and gender-sensitive assistance, without discrimination, including medical care, rehabilitation and psychological support, as well as […] social and economic inclusion” to the individuals under its jurisdiction who are affected by the use or testing of nuclear weapons. In addition, Article 6(2) provides that each State Party “shall take necessary and appropriate measures towards the environmental remediation” of areas under its jurisdiction which have been contaminated as a result of activities relating to the testing or use of Nuclear Weapons.

International assistance and cooperation

Article 7(1) provides that: “Each State Party shall cooperate with other States Parties to facilitate the implementation of this Treaty“. According to Article 7(2), the States Parties have the right to seek and receive assistance from one another in fulfilling their obligations under the Treaty. In addition, under Articles 7(3)-(4), where a State Party is in a position to do so, it shall “provide technical, material and financial assistance to States Parties affected by nuclear-weapons use or testing” and “assistance for the victims of the use or testing of [Nuclear Weapons]”.

Miscellaneous provisions

Article 11(1) governs the procedure for settling disputes between the States Parties to the Treaty. It provides that disputes relating to the interpretation of application of the Treaty shall be settled by negotiation or other peaceful means of the parties’ choice in accordance with Article 33 of the United Nations Charter. This in turn provides that the parties to any dispute shall “seek a solution by negotiation, enquiry, mediation, conciliation, arbitration, judicial settlement, resort to regional agencies or arrangements, or other peaceful means of their own choice“. Under the latter provision, the United Nations Security Council may also call upon the parties to a dispute to settle their dispute by the aforementioned means.

Interestingly, the Treaty contains a “Universality” provision. Article 12 states that “each State Party shall encourage States not party to this Treaty to sign, ratify, accept, approve or accede to the Treaty, with the goal of universal adherence of all States to the Treaty“. In addition, and unsurprisingly, given the nature of the Treaty, Article 16 clarifies that no provisions of the Treaty are subject to reservations, which means that the States which adopted the Treaty are bound by it in its entirety.


Following Honduras’ ratification of the Treaty, the United Nations Secretary-General’s Spokesman stated that “the entry-into-force of the Treaty on the Prohibition of Nuclear Weapons is the culmination of a worldwide movement to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons. It represents a meaningful commitment towards the total elimination of nuclear weapons, which remains the highest disarmament priority of the United Nations“.

The Treaty is the first multilateral and binding instrument for nuclear disarmament to have been negotiated in the last two decades. However, given the absence of a number of significant States from the list of State Parties, particularly those with known nuclear weapons capabilities, it remains to be seen how effective the Treaty will be.

For further information, please contact Andrew Cannon, Partner, Helin Laufer, Associate or your usual Herbert Smith Freehills contact.

Andrew Cannon
Andrew Cannon
+44 20 7466 2852
Helin Laufer
Helin Laufer
+44 20 7466 6425