President Barack Obama is to outline plans for the withdrawal of troops from Afghanistan in a speech on Wednesday.
Officials at the White House and Pentagon said around 10,000 personnel would be back on home soil by the end of the year.
Around 3,000 to 5,000 are expected to be brought home next month. Many of the 30,000 U.S. troops deployed in the 2009 surge would remain in the country until after the presidential election next November.
President Obama is expected to say that the troop reduction has been made possible by the success of forces in dismantling al-Qaida's capability to attack the U.S.
Details of the exact numbers and the speed at which troops will be withdrawn are still to be finalized, but it is understood that these will be left to field commanders to decide.
The U.S.’s top military brass is pressing for a slow pullout in order not to jeopardize precious gains in building up security, particularly in the west.
With the 2012 presidential election on the horizon, however, Obama will also be keen to appease the many Americans eager for an end to 10 years of largely unpopular conflict.
Obama will follow his announcement with a visit to Fort Drum on Thursday. Fort Drum is home to the 10th Mountain Division, which has been deployed to both Iraq and Afghanistan.