drone or remotely piloted vehicle, a pilotless craft guided by remote control. Aircraft, ships, and land vehicles can be designed or outfitted as drones, although underwater vessels—both piloted and pilotless—are usually called submersibles. Small, relatively inexpensive military drones are used as targets in combat practice, while high-performance models may be used in hazardous reconnaissance missions and to carry and launch missiles against enemy targets without exposing pilots and their far more expensive aircraft to antiaircraft fire. Depending on the mission, drones can be equipped with armament, radar, video cameras, lasers, or sensors for chemical or biological weapons; drones typically can stay aloft without refueling for much longer periods of time than piloted airplanes. Guidance of the drone can originate from an airplane, a ship, a ground station, or a satellite link; a satellite link enables a drone to be guided by an operator stationed thousands of miles away. Building upon the successful use of drones in the Second Persian Gulf War and in Afghanistan, the Homeland Security Department adopted unmanned aircraft to track drug smugglers, illegal immigrants, and terrorists along the U.S. borders. In the United States and elsewhere, drones are increasingly used by law enforcement and security agencies. Current and contemplated non-policing uses include monitoring crops, helping fight forest fires, atmospheric and wildlife research, filmmaking, and news reporting. The Federal Aviation Administration is developing (by the end of 2015) operational and safety regulations governing the commercial use of drone.
Early attempts to use unmanned aerial vehicles are documented as early as the U.S. Civil War. Both Union and Confederate troops launched balloons loaded with explosives in the hope that the balloons would come down inside ammunition or supply depots and explode, but the balloons were at the mercy of the prevailing winds and proved largely ineffective. Toward the end of World War II the Japanese launched similarly ineffective high-altitude balloons loaded with incendiary and other explosives in the hope that winds would carry them to the United States, where they would start forest fires. A U.S. project at about the same time, called "Operation Aphrodite," involved using a modified manned aircraft as a cruise missile. The pilot would take off, get the plane to altitude, pass control to a manned aircraft through a radio link, and then bail out. The somewhat more successful German V-1 was essentially an early cruise missile, not a remote-controlled drone. By the Vietnam War the technology to launch and control drones had evolved. Initially, pilotless aircraft equipped with video cameras flew over North Vietnam to provide reconnaissance data; drones were later used to drop leaflets, interfere with electronic communications, and locate surface-to-air missile batteries. By the early 21st cent., small, hand-launched drones were used by U.S. ground forces to scout otherwise obscured areas, and very small bird- and insectlike drones were under experimental development.
See study by N. Friedman (2010).