Abandon Trident at your peril, warn former defence ministers and Forces chiefs A leaked version of the review suggested that building just two new submarines would save £5 billion in upfront costs and a further £1 billion in annual running costs. The former defence secretaries say that ministers would be "weakening our national security" to save a "very small fraction" of the defence budget. They say that only a like-for-like successor would safeguard Britain for another 30 years. The Government has delayed the decision until 2016 under the terms of the Coalition Agreement. The letter to this paper has been signed by defence secretaries who have served under David Cameron, Gordon Brown, Tony Blair and Sir John Major. They say that the Trident programme is "vital" to British interests. "In an uncertain world, in which the number of nuclear weapons remains high and some states are increasing their holding, we should not take risks with our security by downgrading to a part-time deterrent," they warn. It is our view that if Britain is to remain a leading global power with strong defences, nothing less than a continuous-at-sea deterrent will do. The signatories include Dr Liam Fox and Sir Malcolm Rifkind, former Tory defence secretaries, alongside Bob Ainsworth, Lord Reid of Cardowan and Lord Robertson, former Labour defence secretaries. Lord Robertson was also the secretary general of Nato between 1999 and 2004. The letter has also been signed by Lord Boyce and Lord Stirrup, both former chiefs of the Defence Staff. David Cameron "strongly" believes that Britain's nuclear submarines should be replaced, while Philip Hammond, his Defence Secretary, has accused the Lib Dems of a "reckless gamble." Military sources have suggested that halving the number of submarines could leave Britain without a nuclear deterrent for 10 months of the year. The Government has already committed £3billion to exploring a successor to the Vanguard submarine. A Conservative source said: "We expect that the long held Lib Dem claim that there are cheaper alternatives to Trident will be exposed as a myth. It is widely anticipated that that Lib Dem cruise missile based system will be seen as too expensive and not as credible as the Trident system, so they are having to back-track and change their plans by punting for a part-time deterrent instead. The Liberal Democrats have conceded that alternatives to Trident are "no longer plausible" but want a "serious debate" about downgrading the programme. "Are the threats today the same as in the mid 20th century," a Lib Dem source asked. However sources close Nick Clegg, the Deputy Prime Minister and Liberal Democrat leader, said he does not view Trident as a potential "make or break" issue for a further Coalition government the 2015 General Election. They emphasise that halving the size of the Trident programme is just one of the options that will be presented as part of the review. Dr Fox, the former Conservative Defence Secretary, accused the Liberal Democrats of "petty political posturing." He said: "What we are talking about here is the potential reduction of our national security purely for petty political posturing, not out of a great point of principle, but in trying to differentiate themselves from the Labour Party. I cannot think of a worse reason for bringing forward a policy that would put future generations at risk. Labour backed a like-for-like Trident replacement in 2010 and is understood to be deeply sceptical about claims that there are cheaper alternatives. Kevan Jones, Labour's armed forces minister, said he wanted the "minimum credible deterrent" while achieving "maximum value for money." The review is likely to be heavily redacted to reduce any security risk.