The nuclear enterprise
Close to a fifth of the defence budget is committed before conventional forces are funded at all.
What the nuclear enterprise costs
£1 in every £5
£10.9bn
Spent in 2024/25
18% of the defence budget
20%
Expected share, 2025/26
Expected, accounts not yet finalised
up to 25%
Where it is heading
Department’s own expectation
A growing slice of a growing budget
This share is rising at the same time as the total budget is rising towards 3.5% of GDP. A growing slice of a growing pie means nuclear spending grows twice over — which is why the conventional forces question below is not answered simply by "there is more money now".
It is not just warheads
“Nuclear spending” sounds like bombs. Most of this money is not that. The enterprise covers the submarines that carry the deterrent, their nuclear propulsion, the warheads, and the industrial sites and skills behind all of it — Barrow, Derby, Aldermaston, Faslane and Devonport.
That matters for how you read every figure here. Some of this spending buys submarines that would be needed in a conventional war too.
Dreadnought
Four submarines to replace the Vanguard class and carry the UK’s nuclear deterrent from the early 2030s.
£41bn
Programme envelope, including £10bn contingency
Read that carefully. That budget already includes £10bn of contingency. "Within budget" therefore means within a figure built to absorb overruns, not that the original estimate held.
The scale underneath
9
Nuclear programmes each costing over £10bn across their life
Dreadnought is the one people can name. It is one of nine.
Britain’s second nuclear role
The UK is acquiring at least twelve F-35A aircraft to join NATO’s Dual Capable Aircraft mission.
What this is not. This is participation in NATO nuclear sharing, which uses US nuclear weapons under US custody. It is not a second, independently controlled British nuclear arsenal, and Britain still does not have a US-style triad. What changes is that the UK moves from one delivery route — submarines — to a submarine deterrent plus a NATO air-delivered role.
Parliament cannot currently follow the money
The Public Accounts Committee found that the department is not giving Parliament sufficient transparency over its rising nuclear expenditure, and that published information about nuclear programmes is too vague for Parliament to understand what activities they cover, what they cost, and how those costs have changed.
Operational secrecy about nuclear capability is not seriously disputed. The question Parliament raises is narrower: whether secrecy about capability requires secrecy about financial performance. Knowing whether a programme is on budget does not reveal how the deterrent works.
Several nuclear programmes appear on this site with costs, dates or delivery ratings withheld. Where that happens it is marked, rather than left as a blank that looks like an absence of problems.
The argument, both ways
This site does not take a position on whether Britain should have a nuclear deterrent. That is a political judgement, not a statistical one. What the data can show is the trade-off: what the nuclear enterprise costs, what share of the budget it takes, and therefore what is left for everything else.
The case for
- A submarine-based deterrent is survivable: it cannot be destroyed in a first strike, which is what makes it a deterrent rather than a target.
- It is committed to NATO planning, so it contributes to allied deterrence and not only to UK defence.
- The UK and France are the only European NATO members with nuclear weapons. Giving it up would not be reversible on any realistic timescale.
The cost challenge
- Close to a fifth of the defence budget, heading for a quarter, is committed before conventional forces are funded at all.
- That money is not available for air defence, munitions, ships, personnel or drones — the areas the 2025 Strategic Defence Review identifies as needing rebuilding.
- The pressure grows as the deterrent is modernised, so the squeeze on conventional capability tightens over exactly the period the strategy says readiness must improve.
Both columns describe real consequences. The deterrent is genuinely a capability almost no other European state has, and it genuinely consumes money that conventional forces need. Anyone who tells you only one of those is true is arguing, not informing.
Next: the industrial base — where the money lands, and who receives it. Or back to the defence overview.