In the late 1970’s, concern arose among military planners about the aging design (first flight in 1972) of the F-15 and the possible loss of future air superiority of the fighter. Soviet fighters such as the MiG 29 and Su-27 had demonstrated remarkable maneuverability and performance. In addition, fighter technology had taken enormous strides forward with the introduction of stealth, or low observable, technology. There was also growing concern over the increased effectiveness of the Soviet air defense system that posed a highly lethal environment for the F-15. Therefore, the Air Force initiated an Advanced Tactical Fighter (ATF) Program to develop a replacement for the F-15.
In 1981, the Air Force developed a requirement for an Advanced Tactical Fighter as a new air superiority fighter. It would take advantage of the new technologies in fighter design on the horizon including composite materials, lightweight alloys, advanced flight control systems, higher power propulsion systems and stealth technology. Air Force leaders believed these new technologies would make aircraft like the F-15 and F-16 obsolete by the early 21st century. A Mission Element Need Statement for an Advanced Tactical Fighter (ATF) was released in October 1981.
In September 1985 the Air Force sent out technical requests for proposals to a number of aircraft manufacturing teams. The October 1986 Milestone I review directed a DEM/VAL phase prior to entry into EMD. On 31 October 1986, the Air Force awarded each team a $691-million fixed-price contract to build two prototypes: Northrop-McDonnell Douglas' YF-23, and the Lockheed-Boeing-General Dynamics YF-22. In contrast to the F-117A and the B-2, both of which had been point designed for stealth, these two prototypes were the first airplanes ever to blend stealth with agility and high-speed, supersonic cruise capability.