Fuel is mined by Fuel Mine and Advanced Fuel Mine.
A liquid, similar to Earth's crude oil can be used in similar way - to propel ground or flying vehicles including UFO. The more fuel supply we have available, the further the flight range of aircraft taking our soldiers to battles will be. At access level None, UFO can fly only to the neighboring territories. Every level above this increase its radius by one region.
[ TODO: Add territory list ]