How the Next UK Government Could Reduce the Risk of Nuclear War

December 2023
By Louis Reitmann

The next UK general election is due by January 2025, and for the first time in more than 10 years, a win by the Labour Party seems possible. Polling between 44 and 47 percent, Labour is as popular as the Conservative Party was when Boris Johnson won a landslide victory in 2019.1 Remarkably, 62 percent of members of Parliament believe that Labour will win the next election, as do most voters and 48 percent of Conservative voters.2

The administration of UK Prime Minister Boris Johnson of the Conservative Party (L), seen here in 2020, stunned the world in 2021 by raising the limit on the country’s nuclear stockpile. The government of his Conservative Party successor, Rishi Sunak (R),  shows no interest in changing course. (Photo by House of Commons/PA Images via Getty Images)With a potential change in government on the horizon, the United Kingdom has an opportunity to rethink its nuclear weapons policy and return to a leadership role on nuclear risk reduction and disarmament among the five nuclear-weapon states recognized under the nuclear Nonproliferation Treaty (NPT). After decades of reductions, the Johnson government stunned the world in 2021 by raising the limit on the UK nuclear stockpile from 180 warheads to 260 warheads and by reducing arsenal transparency.3 With this decision, the UK lost political leverage over other nuclear powers, further polarized the global disarmament debate, and contributed to growing nuclear risk. The present government of Prime Minister Rishi Sunak has shown no interest in changing course.

Although Labour has criticized Conservative nuclear weapons policy, it is far from united on the issue. The party seems stuck in a cyclical debate about whether to appear tough on defense or pursue nuclear disarmament, but there is a clear path by which a Labour government could take meaningful yet realistic action to reduce nuclear risk and make progress toward disarmament without unilaterally surrendering the country’s nuclear arsenal.

Giving Perspective to a Disillusioned Party

The issue of the UK’s nuclear weapons has been thorny for Labour. Its vocal pro-disarmament wing has exposed the party to questions about its commitment to national defense and nuclear deterrence. Credibility issues intensified under Jeremy Corbyn, the previous party leader and a lifelong disarmament advocate who said that he would never use nuclear weapons if elected prime minister.

The current leader, Keir Starmer, has tried to silence the critics by cementing Labour’s commitment to the UK’s nuclear weapons as “non-negotiable” and by underlining support for the ongoing modernization program.4 More recently, Starmer abolished the Office of Shadow Minister for Peace and Disarmament, held by a lawmaker who campaigned for the country to join the Treaty on the Prohibition of Nuclear Weapons (TPNW).5 In terms of electoral strategy, this seems smart; voters currently prefer Labour policies in all areas except defense, where the Conservatives have an 18-point lead.6 To win the next election, Labour must appeal to more center-right voters, the majority of whom support the UK having nuclear weapons.7

At the same time, Starmer’s Labour Party has condemned the Johnson government for breaking its goal of gradually reducing the stockpile, criticized the Dreadnought-class submarine program’s spiraling cost as wasteful, and pledged to “lead efforts to secure multilateral disarmament.”8 There is a clear desire to differentiate Labour from the Conservative approach without appearing “weak” on defense.

To do so, Labour has to move beyond the limits of its internal debate, which has long been defined by an imagined binary choice between maintaining the arsenal as it is and complete nuclear disarmament, when in reality there are many options in between. If Labour wants to restore UK leadership in the global nuclear order, it should take a long, hard look at them.

Taking Meaningful, Realistic Action

A future Labour government’s nuclear weapons policy should be based on several broad objectives: countering the trend toward nuclear armament, reducing the risk of nuclear war, and easing the tension between the five nuclear-weapon states and TPNW states-parties that undermines a collaborative pursuit of nuclear disarmament. Implementing the following policy options would help achieve these objectives.

The lowest hanging fruit for a Labour government would be to declare a moratorium on increases to the nuclear weapons stockpile enabled by the 2021 Integrated Review of Security, Defence, Development and Foreign Policy. This would leave open the option of growing the stockpile in the future while acknowledging the questionable strategic necessity of a larger stockpile at this moment.

Defense officials at the time said that the cap increase was “driven by a desire to be more assertive and ‘not apologize’ for the UK’s position as a nuclear state,” rather than by strategic thinking.9 Not only was the decision unforeseen by the expert community, it also contained very little detail about the capabilities of adversaries that made a stockpile increase necessary and why alternatives, such as increasing the operational part of the stockpile, arming the patrolling submarine with more than 40 warheads, or enhancing submarine stealth or missile reentry for greater arsenal survivability, were not viable options. Going a step further, a Labour government could reinstate the previous limit of 180 warheads and resume work toward this goal to be completed in the mid-2030s.

Reversing a second decision announced in the 2021 Integrated Review, a Labour government could enhance transparency by resuming publication of the number of deployed UK missiles and warheads, and the size of the operational stockpile. The decision to pursue strategic ambiguity was meant to complicate the decision-making of adversaries during crises, but critics note that there is little evidence that ambiguity about capabilities strengthens deterrence. Indeed, the principal lesson from the Soviet-U.S. arms control experience was that mutual transparency increased both sides’ confidence that credible deterrence was possible even with fewer nuclear weapons.10 Strategic ambiguity raises the risk of miscalculation, which is why governments, such as those involved in the Stockholm Initiative, a cross-regional group of 14 countries committed to advancing nuclear disarmament, have been calling for enhanced information exchanges, dialogue, and transparency to reduce nuclear risk.11

Strategic ambiguity is inconsistent with the UK’s practice of lobbying for transparency and national reporting under the NPT and undermines its ability to credibly criticize Chinese and Russian nuclear secrecy. It also may increase distrust within the P5 process, a consultative mechanism initiated in 2009 to facilitate cooperation among the NPT’s five nuclear-weapon states that the UK inaugurated and shepherds. As former UK Defense Secretary Desmond Browne concluded, “There is really no good explanation for ending this transparency.”12

Adopting a Sole-Purpose Policy

By adopting a sole-purpose policy, the UK would declare that its nuclear weapons are only intended to deter an attack with nuclear weapons, not with any other weapons of mass destruction, conventional weapons, or cyberweapons. This change would reflect the broad consensus in the UK nuclear community that it is unthinkable that London would ever use nuclear weapons first and that the arsenal is too small to deliver a preemptive strike against its main adversaries, Russia and China. There also is no majority support among the UK public for a first-use policy.13

A sole-purpose declaration would be a positive step toward risk reduction, helping to prevent miscalculations by adversaries that could trigger a nuclear first strike against the UK. The argument that retaining a first-use option deters conventional war ignores the fact that even a lower-yield nuclear response to a conventional attack easily could escalate into full-blown nuclear war.

Adopting a sole-purpose policy would require coordination with allies to ensure complementarity with NATO’s nuclear posture. There is potential for the UK and the United States to act jointly on this in the future since the Biden administration was viewed as likely to adopt a sole-purpose policy prior to Russia’s invasion of Ukraine.

Another option is for a Labour-led Parliament to adopt legislation linking future nuclear weapons modernization to further reductions in the stockpile or nuclear posture, affecting updates to the arsenal after the Dreadnought-class submarines now under construction leave service in the 2070s. This would be a long overdue response to criticism that the nuclear-weapon states are not making concrete plans for disarmament in the spirit of the NPT while still giving the UK another 40 years to prepare for reductions.

Although politically difficult, this option must be considered seriously, not least because each modernization bears a considerable risk that the update cannot be delivered on time, at the expected capability, or at all. Currently, concerns are emerging that the Dreadnought program will not be completed; several components are already severely behind schedule and billions over budget.14 Regarding the development of a new reactor to power the submarines, the UK Infrastructure and Projects Authority has concluded that the “successful delivery of the project appears to be unachievable.”15 Facing many challenges from economic security to public health, the UK may not want or be able to take on an immense financial risk like this again.

As for alternatives to the current UK posture with at least one nuclear-armed submarine always at sea, a 2013 governmental review gave concrete options, for example, coordinating deployment schedules more closely with France and the United States to ensure that the UK is protected by NATO capabilities when not deploying its own submarines.16 Reductions in the stockpile or nuclear posture could be combined with a UK Ministry of Defence program to investigate how the state could bolster its conventional capabilities with the savings that accrue from a smaller nuclear arsenal.

Attending a TPNW Meeting

A Labour government could make history if the UK becomes the first nuclear-weapon state to attend a TPNW meeting of states-parties as an observer. This could be a step toward a broader change in the UK approach to the treaty if it no longer works to undermine the TPNW, discourages states from joining it, or asserts the treaty’s incompatibility with the NPT.

Normalizing the UK relationship with the TPNW would be a smart choice. It would acknowledge that the campaign by the nuclear-weapon states against the treaty has backfired by antagonizing many non-nuclear-weapon states and strengthening support for the TPNW. At the same time, a less hostile approach would not prevent the UK from continuing to assert that the treaty has no political or legal effect on itself or other states that are not party to it.

It is worth remembering that the UK previously has changed course in a similar way. After abstaining from the first two conferences on the humanitarian impact of nuclear weapons, in Oslo and Nayarit, the UK and the United States attended the third conference, held in Vienna in 2014, and were the only nuclear-weapon states to do so.

Finally, a Labour government could fund assistance for victims of UK nuclear testing and for restoration of the ecosystems that UK tests have destroyed in Australia, the Pacific region, and Nevada. Assistance could be given directly to the affected communities or via a trust fund that TPNW states-parties are discussing.17

Emphasizing humanitarian and environmental concerns would align well with Labour’s ambitions to carve out a new, progressive role for the UK on the world stage. It also would help address the country’s colonialist legacy as nearly all 45 of its nuclear tests were conducted on or near indigenous land. The UK pays pensions to veterans who worked on the tests, and Labour has promised each veteran a ₤50,000 lump sum.18 Yet, the UK has never extended apologies or support to indigenous peoples who for generations have suffered the trauma and health consequences of nuclear testing. In Kiribati alone, 189 families have been afflicted by illness due to UK tests.19 Despite persistent lobbying, including at the 2023 UN General Assembly, calls for compensation have been ignored.

From an opportunistic perspective, providing such support could further the UK’s self-perception as a responsible nuclear-weapon state. Along with France and the United States, the UK has used this term to differentiate itself from China and Russia, which have embarked on modernization and expansion programs for their nuclear arsenals with minimal transparency.

The UK could even fund assistance to people and places affected by Soviet testing, for example, in Kazakhstan, thus demonstrating the difference between Russian and UK conduct as nuclear powers. TPNW states-parties reject the idea that any state with nuclear weapons could be considered responsible, but expanding the concept to include victims assistance and environmental remediation could strengthen the UK case that there are more responsible ways of maintaining nuclear weapons.

An Opportunity to Be Seized

If elected, Labour must move past its self-sabotaging internal struggle between unconditional commitment to the status quo and unilateral disarmament toward a balanced and results-oriented approach to the country’s nuclear arsenal. Labour’s pursuit of a “safe-choice-for-defense” image should not prevent it from seizing this unique opportunity to restore the UK’s international leadership regarding nuclear risk reduction and disarmament. There are plenty of policy options on the table, from low-hanging fruit to ambitious initiatives.



1. Ipsos, “Latest UK Opinion Polls: Government Approval Recent Changes,” October 4, 2023; YouGov, “YouGov/The Times Survey Results,” n.d., p. 1,

2. Matthew Smith, “Half of Tory MPs Say the Conservatives Are Going to Win the Next Election,” YouGov, July 14, 2023,

3. Kingston Reif and Shannon Bugos, “UK to Increase Cap on Nuclear Warhead Stockpile,” Arms Control Today, April 2021, pp. 18-19.

4. Helen Catt, “Labour Renews Vow to Keep Nuclear Weapons,” BBC News, February 26, 2021,

5. Labour Campaign for Nuclear Disarmament, “Starmer Removes Peace and Disarmament Role From Shadow Team,” September 8, 2023,; Campaign for Nuclear Disarmament, “Parliamentarians Supporting the TPNW,” January 7, 2021,

6. Gideon Skinner et al., “British Public Think Labour Have the Best Policies on Key Issues but Are Often Unsure How They Would Tackle Them,” Ipsos, June 27, 2023,

7. Milan Dinic, “YouGov Study of War: Nuclear Weapons and War,” YouGov, September 21, 2022,

8. Dan Sabbagh and Jessica Elgot, “Keir Starmer Accuses PM of Breaking Policy on Nuclear Disarmament,” The Guardian, March 16, 2021,; Dan Taylor, “Row as Labour Criticises ‘Significant Issues’ With Dreadnought Programme,” The Mail, September 7, 2022,; Helen Catt, “Labour Renews Vow to Keep Nuclear Weapons,” BBC News, February 26, 2021,

9. David Cullen, “Extreme Circumstances: The UK’s New Nuclear Warhead in Context,” Nuclear Information Service (NIS), August 2022, p. 36,

10. Pavel Podvig, “Transparency in Nuclear Disarmament,” UN Institute for Disarmament Research, March 2012, p. 6,

11. 2020 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, “A Nuclear Risk Reduction Package: Working Paper Submitted by the Stockholm Initiative, Supported by Argentina, Belgium, Canada, Denmark, Ethiopia, Finland, Germany, Iceland, Indonesia, Japan, Jordan, Kazakhstan, Luxembourg, the Netherlands, New Zealand, Norway, South Korea, Spain, Sweden and Switzerland,” NPT/CONF.2020/WP.9, May 14, 2021, p. 3.

12. James McKeon, “Q&A: Des Browne on the UK’s Decision to Increase the Cap on Nuclear Warheads,” Nuclear Threat Initiative, April 14, 2021,

13. Tim Street, Harry Spencer, and Shane Ward, “The British Government Doesn’t Want to Talk About Its Nuclear Weapons. The British Public Does,” Bulletin of the Atomic Scientists, April 6, 2023,

14. NIS, “Trouble Ahead Update - Winter 2022/23,” YouTube, December 20, 2022,

15. NIS, “Increasing Risk of Problems in Derby Delaying Dreadnought Schedule,” August 7, 2023,

16. Government of the United Kingdom, “Trident Alternatives Review,” July 16, 2013,

17. International Human Rights Clinic, Harvard Law School, “Designing a Trust Fund for the Treaty on the Prohibition of Nuclear Weapons: Precedents and Proposals,” January 2023,

18. UK Labour Party, “It’s Time for Real Change: The Labour Party Manifesto 2019,” November 2019, p. 101,

19. Becky Alexis-Martin, “Veterans Join Pacific Islanders in Bid for Nuclear Testing Compensation,” The Telegraph, October 19, 2023,

Louis Reitmann is a research associate at the Vienna Center for Disarmament and Non-Proliferation, focusing on nuclear disarmament, export controls, and diversity, equity, and inclusion in the nuclear field.