Syria's foreign minister on Sunday said his country may resort to more "painful" measures if the United States does not give an official explanation for last Sunday's deadly cross-border raid. Syria retaliated to the attack that it says killed eight people by ordering the closure of an American school and cultural center in Damascus.

But Foreign Minister Walid al-Moallem conveyed those measures were "introductory." He warned Syria could escalate its response in the future.

Al-Moallem spoke Sunday in a TV interview with the Lebanese ANB satellite station.