The Mikoyan-Gurevich MiG-15 (NATO reporting name: "Fagot") is a jet fighter aircraft developed by Mikoyan-Gurevich OKB for the Soviet Union. The MiG-15 was one of the first successful jet fighters to incorporate swept wings to achieve high transonic speeds. Introduced in combat over the skies of Korea, it outclassed straight-winged jet day fighters which were largely relegated to ground attack roles, and was quickly countered by the similar American swept-wing F-86 Sabre. The MiG-15 is often mentioned, along with the North American F-86 Sabre, as the best fighter aircraft of the Korean War, and among the best fighter aircraft of all time. When refined with an afterburner into the more advanced MiG-17, the basic design would again surprise the West when it proved effective against supersonic fighters such as the F-105 Thunderchief in the Vietnam War of the 1960s. The return of subsonic daylight dogfights would spur the next generation of fighter design and tactics, and the use of subsonic fighters as aggressor simulators.The MiG-15 is believed to have been one of the most widely produced jet aircraft ever made; in excess of 12,000 were manufactured. Licensed foreign production may have raised the production total to over 18,000. The MiG-15 remains in service with the North Korean Air Force as an advanced trainer.