The General Atomics MQ-9 Reaper (originally the Predator B) is an Unmanned Aerial Vehicle (UAV) (also known as a Remotely Piloted Vehicle (RPV)) developed by General Atomics Aeronautical Systems (GA-ASI) for use by the United States Air Force, the United States Navy, the Royal Air Force, and the Italian Air Force. The MQ-9 is the first hunter-killer UAV designed for long-endurance, high-altitude surveillance.[3]

The MQ-9 is a larger and more capable aircraft than the earlier MQ-1 Predator, although it can be controlled by the same ground systems used to control MQ-1s. The MQ-9 has a 950-shaft-horsepower (712 kW) turboprop engine, far more powerful than the Predator's 115 hp (86 kW) piston engine. The increase in power allows the Reaper to carry 15 times more ordnance and cruise at three times the speed of the MQ-1. Although the MQ-9 can fly pre-programmed routes autonomously, the aircraft is always monitored or controlled by aircrew in the Ground Control Station (GCS) and weapons employment is always commanded by the pilot.

Then U.S. Air Force (USAF) Chief of Staff 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." As of 2009 the U.S. Air Force’s fleet stands at 195 Predators and 28 Reapers.

(Taken directly from Wikipedia.