A couple of points: 1) Fort Knox is an active military base – the storage of gold is in the United States Bullion Depository, which is just a couple of acres on the military base. link So it is safe to assume that primary security protection is by the US Treasury department, but that the Army’s security is dealing with the area in general. Second, Fort Knox is NOT the US Mint. United States coins are made in: – Denver – Philadelphia – San Francisco – West Point, NY The mint is protected by the US Mint Police force.