The United States should be able to begin scaling back its troop presence in Afghanistan from a post-surge peak by 2013, says General Stanley McChrystal , the top U.S. and NATO commander in Afghanistan.
Gen McChrystal gave his assessment to a delegation of U.S. lawmakers who visited Kabul earlier this week, participants said on Saturday.
It is unclear whether President Barack Obama will spell out a schedule for a drawdown of U.S. forces when he announces a revised war strategy on Tuesday.
The centerpiece of that strategy is expected to be the gradual deployment of about 30,000 more U.S. troops to Afghanistan to secure population centers and train more of the country's security forces.
Pentagon officials hope NATO members will contribute up to 10,000 extra troops and trainers to supplement the U.S. buildup, pushing the overall number closer to the 40,000 additional soldiers recommended by McChrystal to counter a resurgent Taliban.
Britain has said it expects countries to pledge another 5,000 troops on top of those sent by the United States.
A drawdown schedule could help Obama blunt opposition to a troop increase within his own Democratic party, which controls Congress. Rising U.S. casualties and military costs have sapped public support for the war, threatening Obama's standing ahead of congressional elections next year.
An international conference on Afghanistan, to be held in London in January, would aim to set conditions for a gradual transfer of security responsibilities to Afghan control.
McChrystal met the visiting U.S. lawmakers on Tuesday.
"I asked him: 'If you get these troops that you are requesting, the 40,000, where's the tipping point? At what point will we begin to draw down?'" Republican Representative Mike Coffman told Reuters. "McChrystal responded: 'Sometime before 2013.'"
White spokesman said that the evacuation of forces from Afghanistan would be completed by 2017-2018.