Nuclear Weapons and The United Kingdom - Number of Warheads

Number of Warheads

Since 1969 the United Kingdom has always had at least one ballistic-missile submarine on patrol, giving it a nuclear deterrent that is what the Defence Council described in 1980 as "effectively invulnerable to pre-emptive attack". In the Strategic Defence Review published in July 1998, the government stated that once the Vanguard submarines became fully operational (the fourth and final one, Vengeance, entered service on 27 November 1999), it would "maintain a stockpile of fewer than 200 operationally available warheads". The Stockholm International Peace Research Institute has estimated the figure as about 165, consisting of 144 deployed weapons plus an extra 15 percent as spares.

At the same time, the UK government indicated that warheads "required to provide a necessary processing margin and for technical surveillance purposes" were not included in the "fewer than 200" figure. As recently declassified archived documents on Chevaline make clear, the 15% excess (referred to by SIPRI as for spares) is normally intended to provide the 'necessary processing margin', and 'surveillance rounds do not contain any nuclear material, being completely inert. These surveillance rounds are used to monitor deterioration in the many non-nuclear components of the warhead, and are best compared with inert training rounds. The SIPRI figures correspond accurately with the official announcements and are likely to be the most accurate. The Natural Resources Defense Council speculates that a figure of 200 is accurate to within a few tens. In 2008 the National Audit Office stated that the UK stockpile was of fewer than 160 operationally available nuclear warheads. During a debate on the Queen's Speech on 26 May 2010 Foreign Secretary William Hague reiterated that the UK has no more than 160 operationally available warheads, and announced that the total number will not exceed 225.