Why does Starmer want to grow Britain's nuclear arsenal?

Spectator

26-06-2025

The government published its National Security Strategy 2025 earlier this week, a strange pushmi-pullyu document building on some policy reviews and anticipating others. It is disappointing and unfocused.
The national security strategy was accompanied by an announcement perhaps just as significant: the government will buy at least 12 Lockheed Martin F-35A Lightning strike fighters which are 'dual capable', that is, they can deliver both conventional and nuclear weapons. These aircraft will give the Royal Air Force a nuclear role for the first time since 1998, and the UK's nuclear capacity will no longer be reliant on the Royal Navy's Vanguard-class ballistic missile submarines.
Keir Starmer has a peculiar and unsettling enthusiasm for the UK's nuclear deterrent
This is significant in all sorts of ways: militarily, conceptually and in terms of doctrine and planning. There are currently nine states with nuclear weapons and the UK is alone in having a single method of delivery, the Trident II submarine-launched ballistic missile. By buying F-35As capable of carrying B61-12 tactical nuclear bombs, Britain can join Germany, Belgium, the Netherlands, Italy and Turkey in contributing to Nato's nuclear sharing arrangement.
Here is the detail, however, and its attendant devil. Nato currently has around 100 of these bombs: they are all owned by the United States and could only be used with the permission of the alliance's Nuclear Planning Group and the American president. There is no suggestion that the UK is likely to develop its own tactical nuclear weapons. Its F-35s would join similar aircraft from Germany, Italy and the Netherlands, as well as ageing F-16 Fighting Falcons from Belgium and Turkey, in being available to conduct nuclear strikes.
The new aircraft will operate from RAF Marham in Norfolk; the existing fleet of F-35Bs are also based at Marham but deploy operationally on the two Queen Elizabeth-class aircraft carriers, which the new F-35As cannot do. (The F-35A is also incompatible with the RAF's Voyager tanker aircraft so will be unable to refuel in-flight.)
The government is not acquiring a sovereign capability here. The aircraft can be used for non-nuclear roles as well, of course, but it would be odd to choose to buy a small number of a different variant from the rest of the force if it was not intended for a specific purpose. We are buying into a nuclear club: helping our allies, certainly, but also paying for a better table, at a cost of around £80 million per aircraft.
These are secondary issues. The more concerning argument is that Nato is strengthening its tactical nuclear capability in order, presumably, to provide a stronger deterrent against Russian or other aggression. President Vladimir Putin has threatened repeatedly to use tactical nuclear weapons in Ukraine, and the logic seems to be that we must be able to match him.
Downing Street described the plan to buy the F-35A aircraft as 'the biggest strengthening of the UK's nuclear posture in a generation'. This is self-evidently true: our policy since at least the end of the Cold War has been to provide leadership on non-proliferation, maintaining a minimum credible deterrence and ruling out using Trident as a first-strike weapon. Now, without any visible heart-searching or hesitancy, the government has decided that the geopolitical situation requires more, not fewer, nuclear weapons, so that it can deliver, in Starmer's words, 'peace through strength'.
There is an argument that low-yield tactical nuclear weapons are de-escalatory, providing more options for varying circumstances and preventing the immediate resort to more powerful warheads.
I am sceptical. Surely it is just as possible that tactical weapons would lower the nuclear threshold, which lies less between tactical and strategic nuclear weapons and more between conventional and nuclear warfare. Smaller tactical weapons are in some ways intended to make 'going nuclear' more, not less, likely.
This is all theoretical. A nuclear weapon has not been used in anger for nearly 80 years, since the 21-kiloton 'Fat Man' bomb was dropped on Nagasaki on 9 August 1945. (The maximum yield of a merely tactical B61-12 bomb is sixteen times that of 'Fat Man'.) What targets would we deem justifiable for tactical weapons? Armoured formations, warships, military installations, infrastructure? What casualties would we see as regrettable but necessary? And once the nuclear threshold is crossed, how do we get back?
Keir Starmer has a peculiar and unsettling enthusiasm for the UK's nuclear deterrent. He brandishes its power and necessity with such muscularity that it sometimes feels like overcompensation for Labour's unilateralism which was set aside nearly 40 years ago. The lead author of the Strategic Defence Review, Lord Robertson of Port Ellen, told Parliament's defence committee that acquiring tactical nuclear weapons was not absent from its recommendations by chance.
The fact that it's not there indicates that we weren't terribly enthusiastic about it. When I was defence secretary the last time round, I got rid of the free-fall bombs.
To modify a catchphrase from the 2010 general election, which feels like a lifetime ago, I agree with George.