The Advanced Tactical Laser (ATL) program was a US military program to mount a high energy laser weapon on an aircraft, initially the AC-130 gunship, for use against ground targets in urban or other areas where minimizing collateral damage is important. The laser was a 100 kilowatt-class chemical oxygen iodine laser (COIL). It was expected to have a tactical range of approximately twenty kilometres and weigh about 5,000–7,000 kg. This program is distinct from the Airborne Laser, which was a much larger system designed to destroy enemy missiles in the boost phase.