Guidance

The UK's nuclear deterrent: what you need to know

Updated 28 March 2024

The UK’s independent nuclear deterrent has existed for over 60 years to deter the most extreme threats to our national security and way of life, helping to guarantee our safety, and that of our NATO allies.

The UK’s independent nuclear deterrent (video)

The threats we face

The risk of nuclear conflict remains remote, but the threats the UK faces are increasing in scale, diversity and complexity. That is why we must be able to deter the most extreme acts of aggression against us and our NATO allies.

The UK has taken a consistent and leading approach on nuclear disarmament but not all states have followed. Some are significantly increasing and diversifying their nuclear capabilities. We must ensure they can never use their nuclear weapons to threaten us, constrain our decision making, or sponsor nuclear terrorism.

To help explain how some states are expanding their nuclear capabilities, NATO have prepared this graphic which uses Russia’s expanding arsenal as an example of this trend and compares it with the systems held by the UK and fellow NATO nuclear weapons states France and the United States. It shows that Russia is significantly increasing the variety of nuclear capable weapons that it possesses. This is in contrast to the work that the NATO nuclear weapons states have undergone to reduce and maintain relatively modest arsenals since the Cold War ended. China also continues to modernise and expand its nuclear capabilities.

It may sometimes feel that these threats are far removed from our daily lives, but the UK must have the capability to protect itself and our NATO allies. Deterrence plays a key role in keeping the public safe, and to abandon our nuclear deterrent would put us all at greater risk.

What is nuclear deterrence?

The purpose of nuclear deterrence is to preserve peace, prevent coercion and deter aggression. Potential aggressors know that the costs of attacking the UK, or our NATO allies, could far outweigh any benefit they could hope to achieve. This deters states from using their nuclear weapons against us or carrying out the most extreme threats to our national security.

It is wrong to say that the UK’s nuclear deterrent is never used. The reality is that it protects us every hour of every day. By providing a credible and effective response option to extreme aggression, our nuclear deterrent reduces the likelihood of such an attack taking place.

The UK’s approach to nuclear deterrence

The view of successive UK governments is that a minimum, credible, independent nuclear deterrent, declared to the defence of NATO, is essential to our security and that of our NATO allies.

Since April 1969, the Royal Navy has maintained continuous at sea deterrence, with at least one nuclear-armed ballistic missile submarine patrolling the seas undetected at all times, ready to respond to the most extreme threats to the UK. Their fundamental purpose is to preserve peace, prevent coercion, and deter aggression.

This continuous at sea deterrent (CASD) is the most capable, resilient, and cost-effective platform on which to deploy our independent nuclear deterrent.

The UK maintains only the minimum amount of destructive power needed to guarantee our deterrent remains credible and effective against the full range of state nuclear threats. Our submarines on patrol are at several days’ notice to fire and, since 1994, we do not target our missiles at any state.

We are deliberately ambiguous about precisely when, how, and at what scale we would use our weapons. This ensures the deterrent’s effectiveness is not undermined and complicates the calculations of a potential aggressor.

The UK’s nuclear deterrent is operationally independent. Only the Prime Minister can authorise the use of our nuclear weapons even if deployed as part of a NATO response. We would consider using our nuclear weapons only in extreme circumstances of self-defence, including the defence of our NATO allies.

Read more information about the UK’s nuclear deterrent, and about Operation Relentless on the Royal Navy’s website. Further details of the UK’s nuclear deterrence policy were set out in the Integrated Review, and were re-affirmed in the Integrated Review Refresh 2023.

NATO and international cooperation

As long as nuclear weapons exist, NATO will remain a nuclear alliance.

Since 1962 the UK has declared our nuclear capability to the defence of NATO. Nuclear deterrence is a critical part of NATO’s overall strategy, and the UK’s deterrent helps safeguard European and Euro-Atlantic security. NATO membership sits at the heart of UK policy, and we are committed to a credible and united nuclear Alliance.

Although the UK’s nuclear deterrent is assigned to the defence of NATO, we retain full operational control over its use. Only the UK Prime Minister can authorise the use of our nuclear weapons, even if used as part of a wider NATO response.

Find out more about the UK’s contribution to NATO, and details of NATO’s approach to nuclear deterrence.

Nuclear remains an important part of our long history of defence cooperation with the United States, enhancing trans-Atlantic security. The UK works collaboratively with the US on nuclear matters including deterrence policy, warhead safety, security and advanced manufacturing technologies. This helps both nations to reduce the development and operational costs of maintaining their independent nuclear deterrents.

The UK has a strong and important relationship with France, and we cooperate daily on nuclear issues to help safeguard European security. This includes our collaboration under the 2010 Teutates Treaty, through which we share research facilities and cooperate on technology.

More widely, we are working with international partners to reduce the threat from nuclear terrorism and on research to support arms control and verification.

The future of the UK’s nuclear deterrent

The UK’s independent nuclear deterrent is relevant not only for today, and it will remain an important part of our national security strategy for as long as the global security situation makes it necessary. Parliament voted decisively in 2016 to renew our nuclear deterrent and maintain CASD. This will be achieved by replacing the existing Vanguard Class submarines with four new Dreadnought Class submarines.

Designed and built in the UK, these new submarines will be some of the most advanced machines ever built, employing world-leading and cutting-edge technology to deliver an extremely capable and intensely formidable capability.

Each year, the government updates Parliament on the progress of the Dreadnought Programme. The programme remains within budget and on track for the first new submarine to enter service in the early 2030s.

As part of the renewal programme, the UK will replace its existing nuclear warhead. We are working with the Atomic Weapons Establishment to build the highly skilled teams, facilities and capabilities needed to deliver the replacement warhead programme. We will continue to work closely with the US to ensure our warhead remains compatible with the Trident Strategic Weapon System, used by both the existing Vanguard Class and future Dreadnought Class submarine fleets.

This investment in our future security will ensure that the UK has a minimum, credible, independent nuclear deterrent for as long as the global security situation makes it necessary. We will continue to keep our nuclear posture under constant review in light of the international security environment and the actions of potential adversaries. We will maintain the minimum capability required to impose costs on an adversary that would far outweigh the benefits they could hope to achieve should they threaten our security, or that of our allies.

Find out more about the Dreadnought programme.

The Integrated Review Refresh 2023 set out measures the government is taking to deliver its commitments to modernise our nuclear enterprise. This was expanded upon in the Defence Nuclear Command Paper, which provides a comprehensive statement of the UK’s defence nuclear policy and sets out the capabilities and programmes necessary to maintain and sustain our independent nuclear deterrent. The Command Paper establishes this mission as a National Endeavour, explaining how by working in partnership with industry and our Allies the UK will tackle the challenges and scale of activity required. This includes ensuring we have the people and specialist skills needed to deliver and sustain our defence nuclear programmes.

The Command Paper represents an unequivocal signal of the UK’s resolve, capability and capacity to implement and deliver the next generation of defence nuclear capabilities needed to protect our people and our Allies from the most extreme threats to our national security and way of life.

The deterrent and the UK economy

Designing, building, maintaining and operating the UK’s independent nuclear deterrent is a national endeavour, directly supporting tens of thousands of jobs across the country.

HM Naval Base Clyde is home to the UK’s submarine service, and its main responsibility is to maintain CASD, which it has delivered safely and securely since 1969 to deter the most extreme threats to our national security and way of life. The base is one of the largest employment sites in Scotland, with thousands of people working there, many of whom chose to make the West of Scotland home after they leave service. 2020 saw the opening of a world-leading submariner training facility as part of plans to develop the base into the UK’s Submarine Centre of Specialisation in a £1.6-billion investment programme.

Submarine construction takes place at the BAE Systems Shipyard in Barrow, where training and apprenticeships are also provided at the Submarine Academy. The nuclear propulsion systems are manufactured by Rolls-Royce in Derby, and Babcock supports and maintains in-service submarines at naval bases in Faslane and Plymouth.

AWE employs thousands of people working on manufacturing, maintaining and assuring the UK’s nuclear warheads, as well as employing approximately 1,700 scientists and engineers, making it one of the largest sciences and engineering employers in the country.

There are around 2,500 companies involved in maintaining the UK’s independent nuclear deterrent through the supply chain, supporting thousands more jobs across the whole of the UK.

The cost of operating, maintaining, and renewing the nuclear deterrent is substantial, but short-term economic pressure does not justify taking long term risks with the security of the UK and our NATO allies. It is an investment in the protection of generations to come, and the ongoing costs form only a small part of the government’s overall defence budget.

The people who make it possible

CASD would not be possible without the skill and dedication of the men and women of the submarine service. They place their duty to protect the UK above all else, missing out on many things we take for granted to help keep us safe.

Generations of Royal Navy submariners, their families, other Service personnel who support the deterrent, civil servants, and industry partners have all contributed to the delivery of the UK’s independent nuclear deterrent for over 50 years.

The submarines need to operate submerged for months at a time, with no option to resupply fresh water, food, or clean air, so they must be self-contained and self-sustaining. The boats are remarkable machines, and the people who work on them truly remarkable individuals.

The safety of our submariners, their families and the general public is of highest priority, and the UK takes the security of its nuclear materials extremely seriously. Storage and maintenance of our nuclear weapons operates under very strict licensing and regulatory requirements, and the weapons are designed with built-in features that make them safe until they may need to be used. We have measures in place to counter and respond to all conceivable incidents, no matter how unlikely. These are regularly tested to ensure their continued efficiency.

Find out what life on board a Vanguard Class submarine is like.

A world without nuclear weapons

The UK remains committed to the ultimate goal of a world without nuclear weapons, and supports the full implementation of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) in all its aspects. There is no credible alternative route to disarmament.

The UK has a consistent and long track-record on nuclear disarmament. We possess the smallest stockpile of nuclear warheads of the five nuclear weapon states (China, France, Russia, the UK and the US), and are the only one to have reduced to a single delivery system.

But the steps we have taken have not led others to follow suit and abandoning our deterrent unilaterally would not lead others to do the same. Instead, it would undermine our security and that of our NATO allies. A world where the UK’s potential adversaries have nuclear weapons and the UK (and NATO) does not, is not a world in which you and your family are safer.

The current security situation requires the UK to maintain an independent, minimum, credible nuclear deterrent to protect ourselves and our NATO allies. We will continue to keep our nuclear posture under constant review in light of the international security environment and the actions of potential adversaries.

But this does not in any way diminish our commitment to progressing nuclear disarmament. The UK believes that the only way to achieve a world without nuclear weapons is through gradual multilateral disarmament. This can be best negotiated through the framework of the NPT, taking account of the wider global security situation. The NPT has played an unparalleled role in restraining the nuclear arms race and minimising the spread of nuclear weapons. It continues to make a significant contribution to international security and stability.

The UK continues to pursue key steps needed for multilateral disarmament, including the entry into force of the Comprehensive Nuclear Test Ban Treaty, and commencement of negotiations on a Fissile Material Cut-Off Treaty in the Conference on Disarmament. We play a leading role by pioneering work on transparency, verification and irreversibility and work closely with international partners, civil society and academia to reduce the risk of nuclear conflict and enhance mutual trust and understanding.

We consider the avoidance of war between Nuclear-Weapon States and the reduction of strategic risks as our foremost responsibilities. In January 2022, the Prime Minister, along with the leaders of China, France, Russia and the United States published, for the first time, a joint statement on preventing nuclear war and avoiding arms races.

The UK has written an open paper to all countries entitled ‘Getting to a world without nuclear weapons’ which sets out the government’s vision for nuclear disarmament. You can find out more about the UK’s work towards a world without nuclear weapons on our NPT Hub, as well as on our Disarmament Blog, and through the Counter Proliferation Programme.

Further information

Find out the truth behind some of the most common misconceptions about the UK’s nuclear deterrent.