When the Pentagon needs to frighten its enemies and rivals, the Air Force deploys fast, radar-evading F-22 stealth fighters or B-52 heavy bombers bristling with weaponry. When threats turn to violence, the Navy and Air Force can call on their huge arsenals of F-15, F-16 and F-18 jet fighters to drop bombs and fire missiles.

For the quieter, more subtle work of spotting, tracking and killing suspected terrorists, the U.S. relies on armed Predator and Reaper drones operated by the Air Force, Army and CIA. And in the difficult, dirty slog of ground warfare, the Army calls on its Apache gunship helicopters and Blackhawk transports and the Marines their controversial V-22 tiltrotors.
But for a wide range of more secretive missions, the Pentagon possesses tiny forces of specialized, and largely unknown, warplanes.