LISBON, Portugal — NATO nations formally agreed Saturday to start reducing troop levels in Afghanistan next year and to hand over control of security to the Afghans in 2014.

But the U.S. and its allies appeared to take conflicting views on when NATO combat operations would end.

NATO Secretary-General Anders Fogh Rasmussen said he did not expect NATO troops to stay in the fight against the Taliban after 2014.

“I don’t foresee ISAF troops in a combat role beyond 2014, provided of course that the security situation allows us to move into a more supportive role,” Fogh Rasmussen told reporters, using the acronym for the International Security Assistance Force that is led by NATO.

But later a senior Obama administration official says the U.S. has not committed to ending its combat mission in Afghanistan at the end of 2014. The official spoke on condition of anonymity in order to discuss internal administration discussions.