How many nuclear warheads does the UK have, and what would nuclear war mean for Britain?

The short answer: no more than 260

The number comes from the government's 2021 Integrated Review. It says that in 2010 the government planned to cut the warhead ceiling from 225 to 180 by the mid-2020s, but that this was "no longer possible" because of the changing security picture. Instead, the UK would move to an overall stockpile of no more than 260 warheads.

Two points people often miss:

• 260 is a ceiling, not a count. The UK's ambassador to the Conference on Disarmament wrote at the time that 260 is a limit, not a target and not the actual number.
• The real numbers are no longer published. The same review says the UK will "no longer give public figures" for its operational stockpile, deployed warheads or deployed missiles. Any exact figure you see online is an outside estimate, not a government number.

What the UK's nuclear weapons are

From the 2021 Integrated Review:

• The warheads are carried by four submarines. At least one is always on patrol, which is called Continuous At Sea Deterrence.
• Submarines on patrol are at several days' notice to fire.
• Since 1994, the missiles have not been aimed at any state.
• The UK aims to keep the "minimum destructive power" needed for the deterrent to be credible.

What changed in 2025. On 24 June 2025 the government announced it would buy 12 F-35A jets that can carry nuclear or conventional weapons and join NATO's nuclear mission. The jets will be based at RAF Marham. The government called it the biggest strengthening of the UK's nuclear posture in a generation, and said it brings back a nuclear role for the RAF for the first time since the end of the Cold War.

When would the UK use them?

The Integrated Review says the UK would consider using nuclear weapons only in extreme circumstances of self-defence, including the defence of NATO allies. It also says the UK is deliberately ambiguous about when, how and at what scale, and won't use or threaten nuclear weapons against non-nuclear states that keep to the Non-Proliferation Treaty.

The point of a deterrent is that it's never used. Knowing the numbers doesn't change what a household should do, so we won't add guesses.

"Nuclear war UK scenario": what's public and what isn't

The government's National Risk Register 2026 is the public summary of the risks it plans for. A footnote says a separate scenario for a nuclear attack on the UK mainland or UK overseas interests exists and is held internally at a higher classification. So there's no public official scenario, target list or map. For why the maps online aren't reliable, read where is safer from a nuclear attack?

What it would mean for your home

The official public advice for any radiation emergency is short. UKHSA and Be Ready call it go in, stay in, tune in:

• Go in. Get indoors as soon as you can. Close doors and windows and keep away from outside walls.
• Stay in. Turn off fans and air conditioning. UKHSA says you may need to stay in for one to two days, possibly longer.
• Tune in. Follow the news and official advice on GOV.UK. A battery or wind-up radio matters if power or phones are down.

UKHSA says food and drink already inside, including tap water, will be safe unless you're told otherwise. That's why a 3-day kit (water, food, radio, torch, medicines) is the useful step, whatever the risk.

Next steps: - What to do if there's a nuclear attack warning - Which room is safest in a house or flat - If the news is making you anxious, how to cope with worry about war

Related guides

• Radiation emergency in the UK: what official advice says (go in, stay in, tune in)
• Worried about war? How UK households can prepare — calmly
• UK Emergency Alerts: a calm guide

We're an independent UK site, not the government. We check guides against official sources and link to them. In an emergency call 999.

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