BRITAIN'S NUCLEAR AND THERMONUCLEAR WEAPONS

Britain's Possession Of Nuclear And Thermonuclear Weapons

Britain's Possession Of Nuclear And Thermonuclear Weapons

A comprehensive Strategic Defense Review was completed by the Labor government in March 1998 that resulted in a major revision in Britain's strategic nuclear posture in July. Effective immediately all WE177 bombs were removed from service, and all of them (175 WE 177 A and B bombs - with yields of 200 and 400 kt) were dismantled by the end of August. This left only a single nuclear weapon system in service - the Trident submarine.

This system too was significantly scaled back. The final seven Trident II missiles that had been planned were cancelled (saving 50 million pounds and writing off another 40 million), leaving the UK with a total missile inventory of 58. The number of submarines on patrol at any given time was reduced to one, and the number of warheads deployed on a submarine was reduced to 48 (half of what had been planned, and identical to the force loading on its previous Polaris fleet). The SDR also announced that Britain would hold its arsenal to "a stockpile of fewer than 200 operationally available warheads". The UK was already believed to have fewer than 200 Trident warheads, although the number could have eventually gone as high as 248 under previous MoD directives. In the fall of 1998 the Trident warhead was still apparently in production but probably ended early in 1999.

The first batch of British Trident warheads were completed in September 1992. They were designed by the Atomic Weapons Establishment (AWE) at Aldermaston, and are assembled at Aldermaston and Burghfield. The warheads are though to have similar characteristics to the U.S. W-76 now on U.S. Trident I and II missiles. The British Trident warheads are capable of selective yield, ranging from under a kiloton up to the full yield of 100 kt or so (this appears to differ from U.S. SLBM warheads). Yields are probably 0.3 kt, 5-10 kt and 100 kt.

In keeping with the reduced operational tempo, only a single crew for each submarine will be maintained. Furthermore the missiles are kept in a de-targeted state. The SDR further declares that "the submarines will routinely be at a 'notice to fire' measured in days rather than the few minutes quick reaction alert that we sustained throughout the Cold War."

The SDR points out that the implied maximum arsenal of 192 warheads "is a reduction of a third from the maximum of 300 announced by the previous government and represents a reduction of more than 70% in the potential explosive power of the deterrent since the end of the Cold War". It is quite possible that the actual warhead stockpile is somewhat smaller than the maximum figure of 192. Only 174 warheads are required to fully equip the entire missile inventory at the specified force loading, but some additional ones would be kept as spares putting the number near 192. However previous practice with the Polaris fleet was to produce only enough warheads ...