Official on al Qaeda commission says Syrian rebel group may have used nerve agent . Peter Bergen : It would not be first time U.N. -affiliated group used chemical weapons . Obama administration raises doubts that rebels used chemical weapons . Such attacks sickened many hundreds of Iraqis , but the victims who died in these assaults did so from the blast of the bombs rather than from inhaling chlorine . Peter Bergen : Issue of who may have used them in U.S. is key to Syria response .
Official on al Qaeda commission says Syrian rebel group may have used nerve agent . Peter Bergen : It would not be first time U.N. -affiliated group used chemical weapons . Obama administration raises doubts that rebels used chemical weapons . Peter Bergen : Issue of who may have used them in U.S. is key to Syria response .