Is Britain's nuclear deterrent cost effective and robust?

With growing Russian threats against the UK this might seem a strange time to question the cost effectiveness of Britain’s nuclear deterrent, but does it offer value for money?

When General Sir Richard Barrons was leading Britain’s Joint Forces Command, he felt there was always what he described as a “tapeworm” eating his budget. “Every year we’d think we’d saved a little for something we needed,” he recalled of his time managing shared capabilities across the services. “It would always go to the Navy for submarines.” Since then, the problem has grown, with Britain’s nuclear deterrent consuming a growing share of the defence budget just as the military is under pressure to re-arm for conventional war.

The issue, Barrons told the Financial Times, was that successive governments had postponed costly decisions about Britain’s nuclear capabilities, leaving several enormous programmes that desperately need to be modernised at exactly the same time. The result is an unprecedented squeeze on the rest of Britain’s armed forces. “The UK’s nuclear budget is eating its conventional budget from the inside,” Barrons, who retired from the role in 2016, told the FT.

Crowding out?

There have been warnings from senior military figures that the rising cost of the deterrent is crowding out investment in the troops, ships, missiles and air defences needed to fight today’s wars. Its cost has taken on added significance as Prime Minister Andy Burnham wrestles with whether to commit to spending 3 per cent of GDP on defence by 2030 — an issue over which John Healey, now chancellor, resigned as defence secretary under Sir Keir Starmer’s government.

The Defence Nuclear Enterprise — the secretive network of organisations responsible for maintaining the UK’s deterrent — spent more than £9bn directly with industry in 2024-25, supports about 47,600 jobs and draws on a supply chain of more than 6,000 companies. By 2030, the government expects the workforce to swell to roughly 65,000, according to figures published by the Ministry of Defence on Tuesday.

At the heart of the spending surge are three vast programmes running in parallel. Britain is building four Dreadnought ballistic-missile submarines to maintain its continuous at-sea nuclear deterrent; designing and preparing to manufacture a new generation of attack submarines with Aukus partners Australia and the US; and developing a replacement for the UK’s nuclear warhead.

Each is a multibillion-pound undertaking in its own right. Together, they require Britain to expand nuclear facilities, shipyards and reactor production, recruit thousands of highly specialised workers and sustain an industrial base capable of delivering nuclear submarines at a tempo not attempted for decades. The overall costs of Britain’s nuclear weapons are difficult to judge as the government does not provide precise breakdowns compared with the detail provided about most other areas of defence spending. The defence investment plan, for example, splits many conventional areas into minute detail but not for nuclear: £47bn is allocated to “submarines” and £13bn is allocated to “warheads”.

Researchers at the International Campaign to Abolish Nuclear Weapons said the official figures actually overstate the cost because they include conventionally armed nuclear-powered submarines. Excluding these would bring the cost from 18 per cent of defence spending in 2025, according to the MoD, to 14 per cent.

This compares to roughly 11 per cent of defence spending for France and 7 per cent for the US, according to ICAN. Meanwhile, UK conventional defence spending is being eclipsed by other Nato countries such as Germany and Poland, both of which spend more as a percentage of their economies than Britain.

The need for scrutiny

The vast sums being spent on a new generation of nuclear weapons and submarines have attracted the attention of parliament. In June, the Commons’ public accounts committee called for more detail to be provided on nuclear spending. Subsequently, the government announced the creation of a committee to scrutinise nuclear spending when parliament returns on September 1. Its evidence sessions will be secret, as will its conclusions, which will be sent directly to the prime minister and the defence secretary.

Britain’s nuclear weapons have always been seen as an expensive luxury in exchange for status as a global power. When Clement Attlee’s government decided in 1947 to proceed with an independent nuclear deterrent, the Treasury was deliberately excluded from meetings to prevent financial concerns from blocking the project.

In 1986, the new Trident submarine-launched ballistic missile system was lampooned on the comedy show Yes, Prime Minister as unaffordable. “In the world of the nuclear missile it [the Trident] is the Savile Row suit, the Rolls-Royce Corniche, a Château Lafite 1945. It’s the nuclear missile that Harrods would sell you,” said one character. But now the UK nuclear deterrent, which consists of more than 200 warheads on sub-launched Trident missiles, has become one of the few calling cards the country has left that ensure it a leading role in Nato.

Despite being operationally independent, the Trident system is quite reliant on the US for support. Missiles are built in the US and go to Kings Bay, Georgia, for maintenance. Britain’s new Astraea warhead is jointly developed with the US W93 warhead programme in order to save costs.

The defence ministry points out launch decisions are made only by the prime minister. “Our nuclear deterrent is the cornerstone of our national security,” said an MoD spokesperson. “It is completely operationally independent and, as we face an increasingly volatile world, it is more important than ever’

Is it robust?

This does raise questions about how robust it is.  The account of the launch procedure that is in the public domain by Lord Hennessey looks fragile.   The prime minister is supposed to use an underground tunnel to the Ministry of Defence and send a fax to a facility near High Wycombe.

No surprise, then, that one of the first tasks of an incoming prime minister is to write a letter to Trident commanders telling them how to proceed if Britain has already been destroyed.

In practice there are back up arrangements that go beyond the public account.  However, keeping one submarine at sea has proved difficult given maintenance problems with the ageing fleet.    Crews have had to spend longer periods at sea away from their families in very cramped conditions (don’t believe the generous sets in the BBC series Vigil about to be screened in a third series).

Failings on defence leave Britain cruelly exposed Former Nato secretary-general Lord George Robertson suggested in testimony to the defence select committee last month that Britain might eventually need European allies to help pay for its nuclear deterrent.   [Or perhaps even cooperate with France?]

Yet with defence budgets under sustained pressure and demands for conventional military capability mounting across Europe, the question is no longer whether Britain can afford its nuclear deterrent but how much conventional military power it is prepared to sacrifice in order to sustain it.