Ten retired senior military officers have written to the prime minister to voice their concerns over the loss of the aircraft carrier HMS Ark Royal.
A former field marshal, three generals and six admirals say the loss of Ark Royal and its fleet of Harrier jets has damaged Britain's defence capabilities.
They say Britain can no longer mount amphibious operations without putting troops' lives at "considerable risk".
Defence Secretary Liam Fox has defended the "difficult decisions".
The BBC's defence correspondent, Jonathan Beale, said the letter, which was leaked to the Daily Telegraph, raises questions about what military rescue operation forces could mount in the future.
In December, Dr Fox announced that the frigate sent to evacuate British nationals from Libya - HMS Cumberland - is to be decommissioned in April, following the strategic defence and security review (SDSR).
Our correspondent says this is not the first time former military top brass have warned that recent cuts in the armed forces have left Britain dangerously exposed.
Labour has already called for the defence review to be reopened in light of events in Egypt, Bahrain and Libya.
The letter - written before the current evacuation operation in Libya - is signed by, among others, Field Marshal Lord Bramall, a former chief of the defence staff; Maj Gen Julian Thompson and Adm Sir Jeremy Black, who commanded the carrier Invincible during the Falklands conflict.
Dr Fox insists Britain still has the "right military assets" in place to respond to crises.
But this group of former military commanders is calling on the prime minister to reassess the decisions made in the defence review.
They have called for a re-evaluation of the SDSR, which they say is "unduly trusting in an uncertain, fast-moving and dangerous world".
However Dr Fox defended the steps taken to tackle the £38bn deficit left by Labour and said the review would not be reopened.
"For our future carrier strike capability, it makes strategic sense to move towards greater inter-operability with the US and France and installing catapult and arrestor gear will deliver this.
"Sustaining both Tornado and Harrier would be prohibitively expensive in this current economic climate and Tornado continues to provide vital support to the front line in Afghanistan," he said.
Referring to Libya, he said Hercules C-130 aircraft had lifted 51 UK citizens to safety on Thursday - and more than 100 were on their way to Malta on HMS Cumberland.
"None of our allies have seen fit to position an aircraft carrier off the coast of Libya as this is not the tool required for this task; there is no requirement for ground attack aircraft, but even if there were we would use our extensive regional basing and overflight rights," he said.
But shadow defence secretary Jim Murphy said: "The government's plans were based on strategic and international geo-political assumptions, many of which have been shaken over the past month.
"Recent dramatic events mean that the defence review must be reopened and perhaps even rethought. It would be sensible to stop and reflect again on our nation's strategic defence needs."