Should the United Kingdom Expand Its Nuclear Capabilities?

The HMS Vanguard, the first of four submarines built to carry nuclear missiles, departs after a seven-and-a-half-year refit in Faslane, Scotland on May 8th, 2023.

Source: Andrew Linnett / Royal Navy Archives

Last Updated

August 01, 2025

Overview

UK policymakers are considering expanding their country’s nuclear capabilities. However, such a course would come at a high cost and could be unpopular. How should they proceed?

Students will understand UK nuclear policy and its political and security context.

Students will appraise various proposed changes to UK nuclear policy.

The Situation

Since 1952, the United Kingdom has possessed nuclear weapons. It has always maintained a far smaller arsenal than the United States and Russia. Its 180–260 warheads (the exact number is deliberately left unconfirmed) places it fifth in the world. By contrast, the United States and Russia each have roughly 4,000 warheads under current arms control arrangements, keeping 1,550 available for use. China and France also have larger stockpiles than the United Kingdom.

The goal of UK nuclear policy has been to maintain a credible deterrent—the ability to threaten a strong enough nuclear response that it dissuades adversaries from launching an attack against the United Kingdom. That deterrent has taken the form of a fleet of four submarines armed with nuclear missiles. At least one submarine is always at sea on patrol to deter a catastrophic attack. The UK’s nuclear weapons are not designed to give it an advantage in a specific conflict. The United Kingdom does not maintain any land-based nuclear missiles. It has also historically not maintained nuclear bombs that can be delivered by warplanes.

On June 2, 2025, the United Kingdom released a strategic defense review that proposed expanding its nuclear posture. The plan ratified a 2016 decision to build a new generation of submarines to maintain the sea-based deterrent. It also called for significant investment in nuclear infrastructure, including building a new generation of warheads. In addition, it called for the United Kingdom to provide greater support to NATO’s nuclear policy, which calls for allied air forces to carry U.S. nuclear weapons in certain situations. The UK government subsequently announced plans to buy F-35A fighter jets that can carry such weapons.

A number of factors drive the recommendation to expand the United Kingdom’s nuclear posture. The security landscape in Europe is less certain than it has been in decades. Russia’s invasion of Ukraine has led to fears that Russia could target other countries in Europe, including NATO member states. If one NATO country is attacked, all have agreed to come to its aid. As a response, NATO members such as Germany, Poland, and the UK have been contemplating significant increases in all forms of defense spending. In addition, many European countries see the United States as a less reliable ally than it once was. President Donald Trump has made public statements questioning the value of NATO and the risk that threats in Europe pose to American citizens. That has led some to wonder if the United States would come to the aid of a European ally in a crisis. The United States failing to defend a NATO member with its nuclear forces would be a significant change to long-standing U.S. and NATO policies.

Domestic factors also drive the shift within the UK. One of the arguments for the United Kingdom exiting the European Union in 2020 was that it could allow the country to pursue its own foreign policy goals and prioritize its own defense, rather than contributing to European goals. Strengthening the UK nuclear portfolio could also support the UK’s sovereignty.

On the other hand, opponents of the UK’s nuclear posture expansion have voiced numerous arguments against additional investment in nuclear weapons. Some have even argued against the UK having any nuclear capability at all. First, the UK nuclear program is expensive. A 2023 parliamentary report found that maintaining the UK nuclear capability costs £3 billion (approximately $4 billion) annually, constituting 6 percent of the national defense budget. Developing new submarines just to maintain the current level of deterrence carries a budget of £41 billion (approximately $56 billion). New warheads and other investments could cost tens of billions of pounds more.

Analysts also question how useful the UK deterrent really is. In a world where the United States and Russia have large nuclear arsenals and China is expanding its arsenal rapidly, they question how credible a deterrent the United Kingdom’s 180–240 warheads truly represent. Finally, the United Kingdom has vocal citizens who oppose nuclear weapons. One recent poll showed 29 percent of British adults oppose the United Kingdom possessing nuclear weapons, and only 40 percent support possession.

Decision Point

About Roles & Goals

UK Cabinet

The prime minister has called a cabinet meeting to discuss UK nuclear posture and whether to move forward with the expansion of nuclear capabilities recommended in the defense review, including the construction of new submarines and warheads, and the purchase of F-35A jets capable of carrying U.S. nuclear weapons. Ministers should weigh the security benefits of such an expansion against its costs. They should also consider public perception issues as they deliberate, including the risk of public protests and political fallout.

Ministers should consider the following three options:

Accept the recommendations of the defense strategic review. This option includes developing a new generation of nuclear warheads and investing in infrastructure and technology that supports the UK nuclear program. It also entails going ahead with the purchase of U.S. F-35A jets capable of carrying nuclear weapons. That option could provide the UK with greater security and flexibility in foreign policy. However, its value—especially at such a high cost—could be questioned.
Keep UK nuclear policy as it is. This entails continuing to ensure a credible submarine-based deterrent, in line with British nuclear policy since the Cold War ended. A new generation of submarines is already approved, but the policy would involve continuing to use the current generation of warheads. It could also include canceling the order of F345A jets or issuing a commitment that they would not be used to carry nuclear bombs. Such a policy could avoid some of the increased costs of the first option. And the United Kingdom would remain as one of only a handful of members of the nuclear club. However, even the current investment in nuclear deterrence is extremely expensive.
Scale back nuclear capabilities. Disarming completely is unlikely to be politically feasible. However, this policy option could entail placing some of the UK’s nuclear warheads in storage, repurposing submarines for delivering conventional weapons or gathering intelligence, canceling the order of F-35A jets, or transferring the UK’s nuclear weapons to the United States or another country. Instead, the United Kingdom could rely on the United States and France to use their nuclear weapons to defend it. Such an option would represent significant cost savings and could satisfy popular opposition. However, it would force the United Kingdom to rely on others for its security and could represent a loss of national prestige in many eyes.