What is the test for possession of a firearm under 18 U.S.C. 924(c) of the Drug Trafficking Act?

Title 18 U.S.C. 924(c) imposes a mandatory five-year minimum term of imprisonment where a defendant "during and in relation to any . . . drug trafficking crime . . . uses or carries a firearm, or . . . in furtherance of any such crime, possesses a firearm." See United States v. Finley, 245 F.3d 199, 206 (2d Cir. 2001) (quoting 18 U.S.C. 924(c)(1)). Possession may be established by showing that the defendant "knowingly [had] the power and the intention at a given time to exercise dominion and control over an object." Id. at 203 (alteration in original) (internal quotation marks omitted). Possession of a firearm is "in furtherance of" a drug trafficking crime within the meaning of 924(c) if there was "some nexus between the firearm and the drug selling operation." Id. "'[I]n furtherance,' means that the gun afforded some advantage (actual or potential, real or contingent) relevant to the vicissitudes of drug trafficking." United States v. Lewter, 402 F.3d 319, 322 (2d Cir. 2005).