Can a defendant be charged with possessing a firearm during the commission of a narcotics trafficking offence?

We review for clear error the district court's determination that a defendant possessed a firearm during the commission of a narcotics offense. United States v. Garcia, 909 F.2d 1346, 1349 (9th Cir.1990).

The Guidelines authorize a two-level upward adjustment in a defendant's offense level if he possessed a firearm during the commission of a narcotics trafficking offense. U.S.S.G. 2D1.1(b)(1). "[W]hen one conspirator possesses a firearm in furtherance of the conspiracy, it may be appropriate to enhance the offense levels of the co-conspirators even if the gun is not actually used and they were not aware of its presence" if "the co-conspirators reasonably should have foreseen that one of their number would possess a gun." United States v. Vargas, 933 F.2d 701, 710 (9th Cir.1991).