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Moving forward on Irreversibility in Nuclear Disarmament

Wednesday 8 – Friday 10 March 2023 | WP3125

Copy of Moving forward on irreversibility in nuclear disarmament (Presentation (169)) (4)

In association with the UK Foreign, Commonwealth and Development Office and the Royal Norwegian Ministry of Foreign Affairs.

Executive Summary

Wilton Park, in partnership with the Norwegian Ministry of Foreign Affairs and the UK Foreign, Commonwealth & Development Office, hosted a dialogue on “Moving forward on Irreversibility in Nuclear Disarmament.” The conversation addressed ways of forging common understandings and commitments on nuclear disarmament, a critical component of the Treaty on the Non-Proliferation of Nuclear Weapons. A key question driving the conversations among participants was whether and how to define irreversible nuclear disarmament (IND). The diversity of approaches to IND would make it difficult to agree on one definition. Still, the dialogue produced a positive attitude towards crafting a shared understanding of what IND entails and demands. IND could be seen as a gradual procedure to build trust and consequences that belong to a broader set of nuclear disarmament instruments and commitments. To conceptualise IND better, the dialogue proposed to identify commonalities among transparency, verification, and disarmament and to think further about the necessary technical, legal, and political mechanisms that guarantee irreversibility.

Crafting a careful narrative about IND is necessary to engage with the larger audiences within the international non-proliferation and disarmament regime. In this effort, there is a need to trace the historical origins and development of IND and be mindful of the past compromises that actors and states have made regarding nuclear disarmament. An attentive portrayal of IND could bring together communities that, even when they disagree on components of the international non-proliferation and disarmament regime, value this set of norms, laws, and organisations and want to sustain it in an international context marked by challenges and competition.


1. The Draft Final Document of the 2022 Review Conference of the Nuclear Non-Proliferation Treaty (NPT) stated that “States parties recognise that further work is required to ensure the irreversibility of nuclear disarmament.”[1] The draft asked to build an understanding of the application of irreversibility measures in attaining and maintaining a world free of nuclear weapons. Wilton Park took up this challenge in partnership with the Norwegian Ministry of Foreign Affairs and the UK Foreign, Commonwealth & Development Office. 

2. Wilton Park organised a dialogue on “Moving forward on Irreversibility in Nuclear Disarmament” to build shared understandings among NPT States Parties and advance the prospects for nuclear disarmament. Wilton Park hosted this conversation in March 2023. This event brought together representatives from States, non-governmental organisations, think tanks, and academia. The 2023 dialogue further advanced work carried out by Wilton Park earlier in 2022 with the goal “to start an international dialogue to better understand and identify requirements” for irreversible nuclear disarmament (IND).[2]

3. The dialogue revolved around how to define and conceptualise IND from a diversity of perspectives. Participants brought to bear their different professional experiences and academic expertise but shared a baseline assumption that IND is crucial to building a nuclear-free world. The intended outcomes of this event were to:

  • Assess the spectrum of positions on IND and work towards a shared understanding of what IND will require,
  • Identify and discuss the technical, legal, and political parameters and criteria for irreversibility, both during a process of disarmament and after disarmament has been achieved, and
  • Explore avenues for taking IND work forward and set out a programme of work that will include the next steps and fora for collaboration.

I organised this report around five key takeaways from these conversations.

[1] 2020 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, Draft Final Document, New York, United Nations, 2022, p. 25, in

[2] “In Preparation for the Wilton Park Dialogue: Irreversibility in Nuclear Disarmament,” Wilton Park, March 2022, in


Different and Diverse Views on Irreversible Nuclear Disarmament

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