by Okopi Ajonye
The 11th Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT RevCon) took place at the UN Headquarters in New York earlier this year. It finished, inevitably, once again, without adopting a consensus final outcome document. Okopi Ajonye analyses some of the issues.
The UK, along with the four other recognised nuclear-weapons states (NWSs), specifically, the US, China, Russia, and France, and 186 non-nuclear weapons states (NNWSs) are signatories to the The Treaty on the Non-proliferation of Nuclear Weapons (NPT) and are collectively recognised as NWSs under the treaty due to the technical status of manufacturing and testing nuclear weapons before 1967. This treaty is composed of three pillars: nuclear disarmament, nuclear non-proliferation, and the peaceful uses of nuclear energy. Taken together, one narrative that has formed around these pillars is that the NNWS agree to not obtain nuclear weapons (i.e. non-proliferation) and only pursue the peaceful uses of nuclear energy in exchange for the NWSs agreeing to pursue nuclear disarmament.
Ever since the NPT came into force in 1970, conferences have been held every five years to review the implementation of the treaty and state actions in support of the treaty’s three pillars, with the first taking place in 1975. The 11th Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (otherwise shortened to NPT RevCon) took place from the 27th of April to the 22nd of May 2026. The P5 process, composed of the five NPT-recognised NWSs, was established by the UK in 2009 for the stated purpose of establishing trust, coordination, and dialogue on nuclear issues. Prior to the latest RevCon, the UK assumed the chair of the P5 process, taking over from China. Like other NPT RevCons since 2010, NPT RevCon 2026 ended without agreement on a consensus document, nor agreed upon actions going forward.
As a NWS, the disarmament pillar is particularly salient for the UK. Prior to the latest RevCon, the UK continued to express support for Article VI of the treaty, which commits the NWSs to pursue negotiations in good faith towards ending the arms race, initiating nuclear disarmament, and formulating a treaty on general and complete disarmament. In an official guidance on the UK’s nuclear weapons system, the UK government affirmed nuclear disarmament as “a core part of our deterrence policy” and committed to continuing to “work constructively towards eventual disarmament and believe this will be best achieved through the framework of the NPT in a step-by-step, transparent, verifiable, and irreversible manner, with undiminished security for all”.
Nuclear disarmament pronouncements repeatedly invoke transparency, verifiability, and irreversibility as essential preconditions for progress towards nuclear disarmament (and the UK government’s statement that “this will be best achieved through the framework of the NPT” is reflective of the fact that, along with the rest of the P5, UK governments have consistently promoted the NPT over the alternative global nuclear weapons treaty, the Treaty on the Prohibition of Nuclear Weapons (TPNW), as the preferred multilateral framework for nuclear non-proliferation and disarmament).
This article will hence briefly outline some issues concerning the UK’s performance on the disarmament pillar of the NPT. While this analysis adopts the common emphasis on transparency, verifiability, and irreversibility as key principles driving nuclear disarmament, it will also briefly examine the role of nuclear risk reduction, as the UK government has declared this principle, along with the previous three, as an essential component of a world without nuclear weapons. These insights will draw on several statements and actions presented by the UK government in its national report to the latest RevCon.
Transparency, Verification, Irreversibility, and Risk Reduction
To demonstrate its commitment to transparency, verification, and irreversibility, the UK government has cited, in its national report, its participation in research and initiatives such as the Quad Nuclear Verification Partnership to promote disarmament verification, the submission of working papers on the concept of irreversibility, and, on transparency, the publication of the Defence Nuclear Enterprise Command Paper and its participation in nuclear risk reduction discussions. Yet, and insofar as these principles promote disarmament, elements of the UK government’s track record on these principles illustrates the limited steps that have been taken towards disarmament.
While the Defence Nuclear Enterprise Command Paper is presented as evidence of the UK’s commitment to transparency in the national report, the defence nuclear enterprise itself has become increasingly opaque and resistant to scrutiny, with reduced information on costs, timescales, and Freedom of Information responses. Moreover, as the command paper states, the UK no longer publishes figures on its operational stockpile and deployed warheads, further reducing transparency. Notably, this diminished transparency has been predicated on the grounds of enhancing “the deterrent effect” of the UK’s nuclear weapons which therefore “reduces the risk of deliberate nuclear use by those seeking a first-strike advantage”. Thus, the UK presents reduced transparency over its operational stockpile and deployed warheads as a means of reducing nuclear risk. This shows the tension between the UK government’s position of endorsing transparency as a principle of nuclear disarmament and preserving strategic ambiguity in support of nuclear deterrence, since the latter can undermine transparency. Should the UK never return to such disclosures, then the transparency needed to build and sustain confidence in its disarmament commitments may be difficult to generate.
For verification, the defence think-tank RUSI (Royal United Services Institute) survey indicated that, in the absence of tangible steps towards nuclear disarmament, the perceived value of the UK’s contributions to nuclear disarmament verification may diminish over time. This lack of progress on nuclear disarmament may also influence how NNWSs perceive the UK’s and other NWSs’ ongoing nuclear modernisation programmes. On the 30th of April during the latest RevCon, some delegates singled out nuclear modernisation along with escalating rhetoric and geopolitical tensions as increasing nuclear risks. Yet nuclear modernisation has often been justified by NWSs such as the UK as needed to ensure the security and safety of their nuclear weapons, and thus reducing nuclear risks.
In the absence of physical progress towards disarmament, such risk reduction measures can reinforce a criticism (made in an article in the International Affairs academic journal) that the risk reduction agenda functions as a “PR” exercise to reassure the public that nuclear weapons can be retained indefinitely and safely while NWSs embark on ambitious nuclear modernisation programmes.
In this view, risk reduction may displace the disarmament pillar of the NPT by (misleadingly) offering the prospect of indefinitely managing, rather than eliminating, nuclear weapons and risks, which can validate critiques that it may become a substitute for nuclear disarmament in the long term. The UK government however clarified in its national report that risk reduction is “not a substitution for disarmament but a vital step towards it.” Still, this assertion would be more credible if it were accompanied by measures demonstrating material movement towards nuclear disarmament.
Regarding irreversibility, in a working paper submitted to the 2026 RevCon, the UK defined the aim of irreversibility as ensuring that “measures taken towards reaching disarmament are not reversed”. When the government initially announced the lowering of its nuclear warhead ceiling to 180 in previous RevCons, it argued that this was in line with its Article VI obligations under the NPT. Therefore, the UK government’s decision in 2021 to renege on this previous commitment and instead raise the warhead ceiling to 260 can be perceived as undermining the irreversibility principle and abandoning a measure that is central to its long-term policy of nuclear disarmament.
Conclusion
The UK’s statements at the 2026 NPT Review Conference demonstrate a continued rhetorical commitment to the principles of transparency, verification, irreversibility, and nuclear risk reduction as means to nuclear disarmament. Yet, the government’s actions show tensions between these principles and its continued reliance on nuclear deterrence and modernisation. If these principles are to serve their intended role as meaningful guides for progress towards Article VI of the NPT, then they may require a clearer and more consistent interpretation and application. As a part of the P5 process, which the UK government has acknowledged as a forum for developing common understanding, the UK is well situated to encourage the NWSs to develop a shared understanding of what transparency, verification, irreversibility, and risk reduction ought to entail in practice, along with mutual expectations for how these principles can support measurable progress towards nuclear disarmament.
Photo credit: UNA-UK