If the U.S. Navy vessel in question was a nuclear-powered submarine, such as a Virginia-class submarine mentioned in some reports, it wouldn’t need nuclear fuel (e.g., enriched uranium) from a private company like Haltbakk Bunkers. Nuclear submarines have their reactors refueled only every 10-30 years, depending on the design, and this is done at specialized military facilities in the U.S., not during routine port calls in places like Norway. So, the fuel refused wouldn’t be for the submarine’s propulsion system.

Instead, the fuel needed would be for auxiliary systems—specifically, marine diesel fuel like NATO F-76 or marine gas oil (MGO). Nuclear submarines carry diesel generators as backups to provide emergency power if the reactor is shut down or to supplement electrical needs for onboard systems (e.g., lighting, electronics, or battery charging) while docked. These generators require conventional marine distillate fuel, which is exactly the type of product a bunker fuel supplier like Haltbakk Bunkers would provide during a port call. A Virginia-class sub, for instance, might use a few thousand liters of diesel for such purposes during a stop, depending on the duration and operational demands. Haltbakk’s refusal to supply "a single liter" of fuel would thus affect these auxiliary diesel needs, not the nuclear propulsion. While inconvenient, the sub could likely operate on existing fuel reserves for a short port visit or refuel via alternative suppliers, as ensured by Norway’s government, making the practical impact more logistical than critical.