DefenceSynergia Short Analysis Of UK Nuclear Doctrine May 2025
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.[1]
In recent days the subject of UK nuclear weapons doctrine has come under scrutiny not least by Sir Simon Case – The Cabinet Secretary until December 2024 – and James Cartlidge MP – former Defence Minister – both suggesting that the Strategic Defence Review 2025, currently unpublished, might also address the UK’s single Nuclear weapons option. DefenceSynergia (DS) has long considered the subject and cautions against a change of policy at this juncture.
The DS position has been stated consistently over a decade and a half: British Nuclear policy is well served by the Continual at Sea Deterrent (CASD) exercised by 4 SSBN carrying Trident II D5 Missiles armed with UK developed and built nuclear warheads or developments of.
DS has also been clear that the threshold between the use of conventional force and the resort to a nuclear option has been continually eroded over 3 decades by the constant reduction in the ‘critical mass’ of UK’s conventional Armed Forces. Arguably, the UK has returned to a nuclear ‘Tripwire’ position because our conventional forces are woefully inadequate.
DS has maintained this consistent position, that for CASD to be credible HMG must provide all the support enablers to ensure its survivability, credibility and certainty – escort vessels and aircraft to sanitise (de louse) the route and accessible maintenance facilities and crew ratios that allow for maximum boat availability and appropriate deployment duration at all times.
The serious underfunding of naval and air forces for CASD support and Conventional critical mass must be resolved before HMG and MOD become sidetracked, primarily because of current US disengagement in NATO, to spend scarce funding on Tactical or Theatre nuclear weapons systems that merely add to the Tripwire.
This does not mean that the UK should not review its nuclear/conventional balance from time to time but in doing so it is important to ensure that the established doctrine is fully funded and supported to allow a level playing field prior to introducing other areas of exotic defence expenditures.
[1] The UK's nuclear deterrent: what you need to know - GOV.UK - March 2024
