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".
The letter to the prime minister has been leaked to the Daily Telegraph.
The BBC's defence correspondent, Jonathan Beale, said the letter raises questions about what military rescue operation forces could mount in the future.
In December Defence Secretary Liam 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.
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; Major General Julian Thompson and Admiral Sir Jeremy Black who commanded the carrier Invincible during the Falklands conflict.
Mr 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.