Commandos would continue missions to kill or capture insurgents and to train Afghan forces while conventional troops begin leaving in July according to reports.
The plan is being debated as commanders are said to be proposing Barack Obama begin the withdrawal by pulling out up to 10,000 troops by the end of this year.
The commander of British forces in Afghanistan warned on Tuesday that the Taliban will exploit a power vacuum in Afghanistan after the 2014 security handover to local forces and that the West must not abandon the country.
"The Afghan people will not necessarily have the confidence to back their own government," General James Bucknall told the Guardian. "And it is important that the regional players understand that the international community is going to be here for some time to come.
"December 2014 is not a campaign end date but a waypoint - a point at which the coalition security posture changes from one that is in the lead to one that is mentoring and advising, but is still here."
America has 100,000 troops in Afghanistan and the killing of Osama bin Laden has rekindled debate on how many are needed now al Qaeda has been decapitated.The US has become increasingly reliant on special forces troops in the 12 months, with Gen David Petraeus crediting raids against militant leaders with helping blunt Taliban momentum.
Advocates of special forces teams have also been emboldened by the success of the US Navy SEALS operation against bin Laden.
Leon Panetta, the CIA director nominated to replace Robert Gates as defence secretary, is also said to favour use of special forces and unmanned drones rather than large numbers of troops waging a costly, counter insurgency campaign.
Under the outline plan, America would keep 20,000 to 30,000 troops on the ground by the end of 2014, when Nato has said it will hand over the combat lead to Kabul.
America's current 10,000-strong special operations forces deployment would remain steady as other troops left.
At present around 4,000 of them are used to kill and capture militants and 6,000 mentor Afghan commandos and raise village-based defence forces. Military planners in Kabul have reportedly drawn up proposals for a withdrawal of as many as 5,000 troops in July to meet Mr Obama's promised deadline to begin his pull out.
