US President Barack Obama said enough progress was being made in Afghanistan to begin withdrawing US troops in July.
Mr Obama said US-led forces were scoring gains against the Taliban and al-Qaeda but warned they were fragile and reversible.
Unveiling a review of his year-old strategy, Mr Obama said the US was on track to achieve its goals.
President Obama announced a year ago as he unveiled a 30,000-strong troop surge to Afghanistan that US troops would begin coming home in July 2011.
NATO partners agreed at a summit last month to set 2014 as the target to cede full control to Afghan security forces.
US Defence Secretary Robert Gates said it was too early to say how quickly troops would be withdrawn, but Washington hoped to accelerate the drawdown as more progress was made.
There are about 100,000 U.S. troops in Afghanistan.
A summary of the review said foreign forces had made "notable operational gains," and reported uneven progress in Pakistan.
It said the United States had made enough progress in Afghanistan in the last year to begin a "responsible reduction" of forces in July 2011.
The review comes at the end of the bloodiest year since US-backed Afghan forces ousted the Taliban as the country's rulers in 2001, with almost 700 foreign troops killed so far.
