The U.S. plans to wind down its war in Afghanistan a year or more earlier than scheduled by ending its combat role in the second half of 2013.

Defense Secretary Leon Panetta said no decision has been made on how quickly to draw down American and other NATO forces, but that the shift away from fighting is being brought forward. At the same time, NATO is considering reducing the planned size of the Afghan army because of the cost involved.

"Hopefully by mid to the latter part of 2013 we'll be able to make a transition from a combat role to a training, advise and assist role," Panetta said on his way to Brussels for a NATO meeting about Afghanistan. "It's still a pretty robust role that we'll be engaged in. It's not going to be a kind of formal combat role that we are [in] now."

The U.S. has about 90,000 soldiers in Afghanistan. Nearly one quarter of the contingent is due to be pulled out by the autumn. The rest were to have been withdrawn by the end of 2014.

Panetta said some NATO forces will remain in Afghanistan until then but in what Washington calls a training and support role.