The United States is planning to keep 9800 troops in Afghanistan for the rest of this year with a complete pullout by the end of 2016.
The US flag is lowered in Laghman province in 2012. Photo: AFP
Some 32,000 American troops are currently stationed in Afghanistan
Under a plan announced at the White House on Tuesday by President Barack Obama, the US will then gradually withdraw troops until only a small residual force remains after 2016.
The remaining troops would guard the US embassy, train Afghan forces and support counter-terrorism operations.
However, the plan depends on the Afghans signing a joint security agreement, the BBC reports.
President Hamid Karzai has refused to sign such an agreement, but the Obama administration appears to be confident both of the two candidates seeking to replace him would do so.
A run-off election between Abdullah Abdullah and Ashraf Ghani to replace Mr Karzai is set for 14 June.
Mr Obama noted on Tuesday that both have said they would sign a security agreement with the US.
All British combat troops are due to leave by the end of this year.
Mr Obama paid a surprise visit to US troops in Afghanistan on Monday, Memorial Day.