The General Atomics MQ-9 Reaper (sometimes called Predator B) is an unmanned aerial vehicle (UAV, one component of an unmanned aircraft system (UAS)) capable of remotely controlled or autonomous flight operations, developed by General Atomics Aeronautical Systems (GA-ASI) primarily for the United States Air Force (USAF). The MQ-9 and other UAVs are referred to as Remotely Piloted Vehicles/Aircraft (RPV/RPA) by the USAF to indicate ground control by humans.[2][3] The MQ-9 is a larger, heavier, more capable aircraft than the earlier General Atomics MQ-1 Predator and can be controlled by the same ground systems. The Reaper has a 950-shaft-horsepower (712 kW) turboprop engine (compared to the Predator's 115 hp (86 kW) piston engine). The greater power allows the Reaper to carry 15 times more ordnance payload and cruise at about three times the speed of the MQ-1.[4] The aircraft is monitored and controlled, including weapons employment, by aircrew in the Ground Control Station (GCS).[5] The MQ-9 is the first hunter-killer UAV designed for long-endurance, high-altitude surveillance.[4] In 2006, Chief of Staff of the United States Air Force General T. Michael Moseley said: "We've moved from using UAVs primarily in intelligence, surveillance, and reconnaissance roles before Operation Iraqi Freedom, to a true hunter-killer role with the Reaper."[4] The USAF operated over 300 MQ-9 Reapers as of May 2021.[1] Several MQ-9 aircraft have been retrofitted with equipment upgrades to improve performance in "high-end combat situations", and all new MQ-9s will have those upgrades. 2035 is the projected end of the service life of the MQ-9 fleet.[1] The average unit cost of an MQ-9 is estimated at $33 million in 2023 dollars.[6][7] The Reaper is also used by the U.S. Customs and Border Protection and the militaries of several other countries. The MQ-9A has been further developed into the MQ-9B, which (based on mission and payload) are referred to by General Atomics as SkyGuardian or SeaGuardian.