The pace of UK troop withdrawals from Afghanistan between now and 2015 will be determined by conditions on the ground, ministers have insisted, after President Barack Obama announced a large-scale pull-out of US forces.
In a key turning point for the conflict, Mr Obama used a televised address to reveal he was ordering home 10,000 American personnel by the end of this year and the other 23,000 deployed in a 2009 "surge" by the end of next summer.
The announcement may ease the way for speedier British withdrawals ahead of Prime Minister David Cameron's "deadline" of 2015 for the end of UK combat operations in Afghanistan.
Mr Cameron has said that 450 British personnel will leave Afghanistan this summer and there are expectations that he will shortly announce a second withdrawal later in the year, with another next autumn. But the Prime Minister insisted that any withdrawals in advance of 2015 would only be made "where conditions on the ground allow".
"The surge by the US and international partners, supported by an increase in the number of Afghan army and police, has reversed the momentum of the insurgency and created the right conditions for security responsibility to begin to transfer to the Afghans from July," he said.
"We will keep UK force levels in Afghanistan under constant review. I have already said there will be no UK troops in combat roles in Afghanistan by 2015 and, where conditions on the ground allow, it is right that we bring troops home sooner."
It was a message he conveyed to Mr Obama in a telephone conversation yesterday and was reiterated by Foreign Secretary William Hague - who is currently visiting Afghanistan - and Defence Secretary Liam Fox.
Chief of the defence staff General Sir David Richards said he welcomed Mr Obama's announcement but stressed that military efforts must continue until the Afghan forces could take responsibility for themselves, saying: "The Afghan army and police are increasingly able to plan, direct and execute operations to provide security for their own people.
"But our collective military efforts need to continue until Afghan security forces are able to assume responsibility for security across Afghanistan by the end of 2014."
Shadow foreign secretary Douglas Alexander said the military drawdown had to be "matched by a diplomatic and political build-up" ahead of the 2014 transfer of security control to Afghan forces.