In the most public indication yet of the size of Britain's deterrent, Mr Rifkind told the Centre for Defence Studies in London that when Trident was fully in service, the total explosive power of the nuclear inventory would be more than 25 per cent down on 1990.
Scotching a revived Labour argument over ordering a fourth Trident submarine, Mr Rifkind said a fleet of four remained necessary to provide 'an adequate minimum deterrent', ensuring one boat could always be at sea. But he said the Government had long made clear that it did not intend to use the full capability of the system and each submarine would not carry more than 128 warheads.
'In fact, I can now confirm that, on the basis of our current assessment of minimum deterrent needs, each submarine will deploy with no more than 96 warheads, and may carry significantly fewer . . . the total explosive power carried on each Trident submarine will not be much changed from Polaris.'
The far greater number of warheads per boat - a maximum of 48 had been predicted - underlined the increasing emphasis being given to Trident's role in sub-strategic deterrence. The US-manufactured missiles could be fitted with fewer warheads, even just one, and these could be of smaller explosive yield.
Rear-Admiral Jonathan Tod, an Assistant Chief of Defence Staff responsible for nuclear policy, said after Mr Rifkind's speech that warheads were already in production at the Atomic Weapons Establishment at Aldermaston in Berkshire. Mr Rifkind added that he did not think the decision would affect jobs at Aldermaston. Any savings would be 'very modest indeed' compared to the pounds 10bn capital cost of the Trident system. Individual warheads cost hundreds of thousands of pounds, not millions, he said.
David Clark, Labour's defence spokesman, said what counted in arms negotiations was warheads, not explosive power. The decision to increase the number of warheads could 'fatally undermine' the Nuclear Non-Proliferation Treaty - to which the Secretary of State had attached renewed importance in an unstable world.
'Mr Rifkind's professed concern over non-proliferation is a sham,' Mr Clark said. 'After all, if a nuclear bomb drops, the size is more or less irrelevant.'
Janet Bloomfield, the newly elected chair of CND, regretted that Mr Rifkind's announcement had not put her out of a job. She said the increased sub-strategic role for Trident suggested the Government had 'shifted from its 'nuclear weapons as a deterrent' argument to intending to use them for fighting 'small' nuclear wars'.Reuse content