U.S. Defense Secretary Leon Panetta says the United States and NATO will seek to end combat operations in Afghanistan in the second half of next year and switch to training and advising Afghan troops through 2014.

Panetta made the comment Wednesday aboard his plane enroute to a NATO meeting in Brussels. He told reporters traveling with him that “hopefully by the mid- to latter part of 2013 we will be able to make a transition from a combat role to a training, advise and assist role.”

The U.S. defense chief called 2013 a crucial year for the final transfer of remaining areas to Afghan security forces. He said no decisions have been made about the level of U.S. forces remaining in Afghanistan once that combat role has ended.

His comments mark the first time the Obama administration has suggested that the end to the U.S. and NATO combat mission in Afghanistan will come in 2013.

NATO defense ministers meet in Brussels this week to discuss a wide range of issues, including the way forward in Afghanistan. Their gathering comes in the wake of French President Nicolas Sarkozy's announcement that he wants his nation's combat troops out of Afghanistan in 2013, a year ahead of schedule.

NATO Secretary-General Anders Fogh Rasmussen said Monday the alliance will adhere to its plans outlined in November 2010, to withdraw combat troops from Afghanistan by the end of 2014, and that NATO nations, including France, will continue their training mission in Afghanistan beyond 2014.