 Each of these aircraft offered unique capabilities to the Soviet military.The MiG-15 was employed primarily against American forces during the Korean War, and proved to be highly successful.The MiG-17, −19, and −21 continued to improve upon this design, as each model reached progressively greater speeds; The MiG-19 was Russia's first supersonic jet to be produced in industrial quantities, and the MiG-21 attained speeds in excess of Mach 2.