Now, two unmanned spy drones are under development. One that appears almost ready for combat is the RQ-180, a stealthy spy drone built by Northrop Grumman. Though the Pentagon refuses to confirm its existence, Aviation Week & Space Technology ran this artist’s concept earlier this year and revealed a little about its rumored design.

The RQ-180 is designed to fly very high, for a very long time (perhaps as long as 24 hours). According to Aviation Week, it has a 130-foot wing span and a “cranked kite” stealthy design that would allow it to slip past enemy radar. Chances are it will only be used for surveillance, not attack, though it could carry out an electronic attack.

Another, recently revealed project is a high-altitude drone being developed by Lockheed Martin that can travel up to six times of the speed of sound. The drone would be both a spy and strike aircraft, according to Lockheed. But the SR-72, as Lockheed is calling the twin-engine aircraft, wouldn’t be ready to fly until 2030.