The Mikoyan-Gurevich MiG-15 was first introduced in 1949. The jet fighter was developed by Mikoyan-Gurevich for the Soviet Union. The MiG-15 was one of the first successful jet fighters to incorporate swept wings to achieve high transonic speeds. In combat over 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 North American F-86 Sabre. The MiG-15 is considered to be the best fighter aircraft of the Korean War. It is still in current service with the North Korean air force.