The increase in warhead numbers announced in the recent Integrated Review of Security, Defence, Development, and Foreign Policy has already commenced and may even be nearing completion, according to an analysis by Nukewatch of nuclear warhead convoy journeys conducted over the last decade.
In March 2021, as part of the Integrated Review, the government announced that the UK will move to an overall nuclear weapon stockpile of no more than 260 warheads. Nukewatch has prepared a technical note to explain the announcement in the Integrated Review in the light of our monitoring of warhead convoy movements between the Atomic Weapons Establishment (AWE) in Berkshire, where they are manufactured and serviced, and the Royal Naval Armaments Depot in Coulport in Scotland, whether they are stored.
Our analysis shows that in the first part of the decade (2010 – 2015) there was a slow but steady reduction in numbers of warheads in the UK warhead stockpile held at Coulport. However, from 2015-6 onwards this trend is reversed, and there has been a net transfer of warheads from AWE to Coulport, resulting in an increase in the stockpile held by the Royal Navy. There has been a marked upturn in the rate of delivery of warheads from AWE to Coulport over the past two years, 2019 and 2020.
Nukewatch believes the initial reduction in warhead numbers can be explained by measures to bring the UK warhead stockpile to below 180, as pledged in the 2010 Strategic Defence and Security Review by the then Conservative – Liberal Democrat government. From around 2015/16 AWE commenced delivery of the Mk4A upgrade of the UK Trident warhead to the Royal Navy, and increases in the stockpile observed since 2015-16 represent deliveries of newly manufactured Mk4A warheads. Assuming a 2010 baseline of 225 warheads in the stockpile, on the basis of our assessment Nukewatch estimates that the UK warhead stockpile had grown to around 250 warheads by December 2020.
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