Britain could start withdrawing troops from Afghanistan next year, Prime Minister David Cameron told BBC radio on Wednesday after talks with US President Barack Obama.
Cameron, who took office two months ago, said in June he wanted British troops home before the next general election, due by May 2015.
But he went further on Wednesday following talks at the White House, saying Britain could begin scaling back its 9,500-strong deployment in Afghanistan in 12 months' time, if local forces could handle responsibility for security.
Obama has said he plans to reduce US troop levels from July in 2011.
Asked by the BBC if Britain could do the same, Cameron said: "Yes, we can but it should be based on the conditions on the ground.
"The faster we can transition districts and provinces to Afghan control, clearly the faster that some forces can be brought home.
"I don't want to raise expectations about that because that transition should be based on how well the security situation is progressing.
"People in Britain should understand we're not going to be there in five years' time, in 2015, with combat troops or large numbers because I think it's important to give people an end date by which we won't be continuing in that way.
"But I hope that with the strategy we have, the build-up of the Afghan army, the transitioning of districts of provinces, as the president said, it will be possible to bring some troops home."
At a conference in Kabul on Tuesday, the international community endorsed sweeping Afghan government plans to take responsibility for security by 2014, forge peace to end nine years of war and take greater control of aid projects.
The majority of Britain's troops in Afghanistan are engaged in battling Taliban insurgents and training local forces in the violence-wracked southern Helmand Province.
A total of 322 British troops have been killed in Afghanistan since the start of operations there in 2001, at least 283 of them as a result of hostile action.