The aircraft has 14,000 litres (3,700 gal (US)) of internal fuel, and its engines are quite thirsty, especially when the afterburner is active. Fuel was contained within integral tanks within the wings, as well as a double-skinned section of the fuselage between and outboard of the inlet ducts, underneath the ducts and engines, and forward of the main spar of the tail fin; this provided a total internal capacity of . A refueling probe is built into the nose; aerial refuelling was often necessary in operations as the Mirage IV only had the fuel capacity, even with external drop tanks, to reach the Soviet Union's borders, thus refuelling was required to allow for a 'round trip'. In the event of nuclear war between the major powers, it was thought that there would be little point in having the fuel to return as the host air bases would have been destroyed; instead, surviving Mirage IVs would have diverted to land at bases in nearby neutral countries following the delivery of their ordnance.