(c) The island is not suitable for the use of mechanical vehicles. It is considered that few, if any, would be landed. (d) As the landing of air-borne troops is limited by the number of suitable aircraft available, and such aircraft are not likely to be available whilst fighting continues in Russia we have dismissed the possibility of an air descent. Naval Aspect 6. The Germans could give immediate naval support to a seaborne expedition with five destroyers already in Northern Norway. U-boat patrols could be established in the vicinity within four days.