Pugwash Note on Nuclear Weapon Announcements in the United Kingdom’s Integrated Review of Security

14 May 2021

The below text is the summary and conclusion of a commentary by Ambassador Peter Jenkins, Chair of the British Pugwash Group. The full text can be downloaded here:


The United Kingdom government recently announced, in the context of an integrated policy review, that it will move to an overall nuclear weapon stockpile of no more than 260 (from a previous target of no more than 180) and that it will extend its longstanding policy of deliberate ambiguity by no longer making public figures for its operational stockpile, deployed warheads and deployed missiles.

These decisions are best seen as symptomatic of a belief that the United Kingdom’s and NATO’s security environment has been deteriorating and that now Russia in particular poses a grave threat to the Kingdom and its NATO allies. Pugwash has an opportunity to react constructively to the decisions by exploring the reasons for the heightening of NATO/Russian tensions in recent years.

Additionally, use of nuclear weapons against non-nuclear aggressors in certain circumstances is envisaged ( extension to the policy of deliberate ambiguity may be connected to this) and the right to review the UK’s negative security assurance to Non-Nuclear Weapon States is reserved. But nuclear weapon use in response to cyber-attacks and against non-state actors is ruled out, and the UK’s nuclear weapon submarines will remain at several days’ notice to fire.


These changes in the UK’s nuclear policy are regrettable. They amount to a step backwards and away from the vision of a world free of nuclear weapons. They call into question the sincerity of the UK’s advocacy of “step-by-step” movement in the direction of that vision. They raise doubt about the strength of the UK’s commitment to full implementation of the Nuclear Non-Proliferation Treaty. They demonstrate that the United Kingdom is still wed to the doctrine of nuclear deterrence.

However, it would seem best for the Pugwash movement to channel concern over these decisions into a constructive initiative. One option would be for Pugwash to explore in some detail why the UK government (probably in the company of other NATO governments) has come to believe that Russia now poses a much graver threat to NATO than UK governments believed in 2010 and 2015. Such work would open up the possibility of Pugwash trying to contribute to a reduction in NATO/Russian tensions and would complement work to prevent a resumption of the nuclear arms race (see Pugwash Note on Arms Control and Disarmament, January 2021).

It is probably fanciful to imagine that the mutual confidence which characterised relations between Russia and NATO in the years that followed German re-unification can be re-built.  But there is room for each side, NATO governments and the Russian government, to clarify the motives behind recent forms of behaviour that the other side has found objectionable, and to draw up mutually acceptable rules of the road for future co-existence.  

The current climate of mutual incomprehension, suspicion and fear, of which the UK’s latest strategic review appears to be a product, is pregnant with nuclear risk on both sides of the NATO/Russian border.

Peter Jenkins
Chair of British Pugwash

14 May 2021