NATO's top official is backing a plan to hand over lead security responsibilities in Afghanistan to Afghan forces sooner than originally envisioned. But he cautioned there are no plans to leave Afghanistan early.

NATO Secretary-General Anders-Fogh Rasmussen spoke Thursday, before entering a meeting of NATO defense ministers in Brussels. He said starting in mid-2013, Afghan security forces will “take the lead” and coalition troops will gradually change from “combat to support.”

The NATO secretary-general said the alliance will stand by its plan to wind up operations in Afghanistan by the end of 2014.

U.S. Defense Secretary Leon Panetta and French President Nicolas Sarkozy have each suggested the coalition should end its combat role in 2013. Mr. Sarkozy announced earlier this month that his country would withdraw its combat forces from Afghanistan in 2013 — a year earlier than planned.

The NATO defense ministers are discussing refining the alliance's timeline for its operations in Afghanistan, and hammering out the details of a longer-term partnership with Kabul.

The U.S. defense chief has 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.

Thursday's NATO meeting in Brussels is being held just days after a leaked coalition report revealed that members of the Taliban insurgency are confident they can regain power in Afghanistan once coalition troops have departed.

The meeting is meant to lay the groundwork for a larger NATO gathering set for Chicago in May.