Britain can maintain a credible nuclear deterrent without a like-for-like replacement of its Trident submarine fleet, a review by the Liberal Democrats has concluded.
The review, led by Treasury Chief Secretary Danny Alexander, said there are alternatives to the UK's current nuclear stance which requires at least one nuclear-armed submarine always to be at a sea.
However, it accepts that cutting the size of the current four-vessel fleet would not offer the same degree of resilience as the current continuous-at-sea deterrent and would not guarantee "a prompt response in all circumstances".
The review was launched by Prime Minister David Cameron and Deputy Prime Minister Nick Clegg as part of the coalition agreement - reflecting the Lib Dems' opposition to a like-for-for like replacement for the Trident submarine fleet - which the Tories strongly support.
Mr Cameron reiterated that the review did not change current Government policy - with the key decisions on whether to go ahead not due to be taken until 2016 after the next general election.
The review concluded: "The analysis has shown that there are alternatives to Trident that would enable the UK to be capable of inflicting significant damage such that most potential adversaries around the world would be deterred."
"None of these alternative systems and postures offers the same degree of resilience as the current posture of continuous at sea deterrence, nor could they guarantee a prompt response in all circumstances."