The withdrawal of British forces from Afghanistan, due by the end of 2014, could be accelerated if the US judged it was safe, the Defence Secretary, Philip Hammond, said.
As well as removing troops from harm's way, an early departure would have a financial benefit, as the UK's presence in the country costs about £3bn a year. But the move would alarm commanders who fear leaving too early would jeopardise gains made at the cost of British lives, and retained by "boots on the ground".
Britain has 9,500 troops in Afghanistan, with 500 to be pulled out of Helmand this year. Mr Hammond said: "We haven't yet decided what the profile of the draw-down is going to be between this autumn … and the end of 2014. That is something we will look at towards the end of this year when we understand better what our allies in Afghanistan are planning."