Drones for military use are typically classified in three broad categories: UAVs (Unmanned Aerial Vehicles), UGVs (Unmanned Ground Vehicles) and USVs (Unmanned Surface Vehicles). UAVs are either remote controlled aircraft (e.g. flown by a pilot at a ground control station) or can fly autonomously following pre-programmed flight plans or more complex dynamic automation systems. The US military uses UAVs for missions ranging from reconnaissance to combat. Most generally, UAVs are capable of “controlled, sustained level flight and powered by a jet or reciprocating engine.” While a cruise missile can also be considered to be a UAV, it is treated separately on the basis that it is considered a weapon. To reflect on the complex nature of modern autonomous systems that include ground stations and other elements besides the actual air vehicles, the US military now uses the term “Unmanned Aircraft Systems” (UAS). To read more click on the link below.