What is the test for a finding that a defendant possessed a firearm during the commission of a drug offence?

We review for clear error the district court's finding that a defendant possessed a firearm during commission of a drug offense. United States v. Kelso, 942 F.2d 680, 681 (9th Cir.1991).

The district court must increase the offense level by two levels if the defendant possessed a dangerous weapon during a drug offense. U.S.S.G. 2D1.1(b)(1). The district court may decline to apply the enhancement only if "it is clearly improbable that the weapon was connected with the offense." Id., comment. (n. 3); United States v. Willard, 919 F.2d 606, 609 (9th Cir.1990), cert. denied, 112 S.Ct. 208 (1991). The defendant bears the burden of showing that a weapon he possessed was not connected to the drug offense. United States v. Stewart, 926 F.2d 899, 900-01 (9th Cir.1991).