David Cameron has insisted the coalition is protecting Britain's future security as he confirmed deep cuts to the armed forces.
The Prime Minister said the Ministry of Defence's budget would fall 8 per cent in real terms by 2015. He also said army numbers would drop 7,000 and navy 5,000 over the same period.
The Nimrod aircraft programme is to be cancelled and there will be fewer frigates and destroyers - but two aircraft carriers will be built.
Of the strategic defence and security review, the Prime Minister said it was "not simply a cost saving exercise", even though money was tight.
"This review sets out a step change in the way we protect this country's security interests," he added.
The RAF will also shed 5,000 personnel by 2015, while 25,000 civilian staff will go from the MoD by the same time.
Mr Cameron attacked Labour for leaving a £38 billion funding gap in the MoD budget.
He insisted the government would remain within the 2 per cent of GDP target for Nato countries' investment in defence.
After the reductions, the UK would still have the fourth largest military in the world, Mr Cameron told the Commons.
"Britain has traditionally punched above its weight in the world and we should have no less ambition for our country in the years to come," he added.
Mr Cameron stressed that the cuts would not affect operations in Afghanistan, which are funded from the Treasury's special reserve rather than the MoD budget.