The outgoing head of the armed forces has warned that the Government might as well scrap Britain's nuclear deterrent if the decision is taken to downgrade it.
Air Chief Marshal Sir Jock Stirrup said any lesser replacement for Trident would not be "credible".
The comments came amid a growing row over the cost and shape of the UK's nuclear capability, with speculation that weapons might not remain continuously deployable in future.
Senior Tories have expressed alarm at reports that the Government could put off the final decision on whether to go ahead with the replacement of the four Clyde-based missile-carrying submarines - due to be announced in 2014 - until after the election in 2015.
Giving evidence to the Commons Public Administration Committee, Sir Jock stressed that it was for politicians to decide whether the UK should have a nuclear deterrent.
But assuming the Government's commitment to that principle, the Chief of the Defence Staff said: "We have to have the minimum credible deterrent.
"If you are not going to have that, then you are better off having zero.
"Spending money on a less than minimum credible deterrent makes, to me, no strategic sense at all."
He went on: "I would be worried about any proposition that was untenable in the context of maintaining the minimum credible nuclear deterrent, which, to me, is continuous at-sea deterrence by a submarine."