The Soviet Union's Air Defense Forces (VPVO) required a slew of heavy interceptors to patrol its vast borders during the Cold War. Most regular "light" fighters, such as the early MiGs, lacked the range and speed to rapidly climb and intercept supersonic American bombers.
However, at the time, the MiG-25 "Foxbat" was also in development. This aircraft would go on to become the VPVO's definitive interceptor.
Nowadays, the MiG-31 is now the Russian Air Force's standard long-range interceptor and is expected to serve until the 2030s. The MiG-31BSM, a "mid-life upgrade," is currently being procured. This upgrade integrates a slew of new strike weapons and modernizes the MiG-31's systems. The MiG-31 was also selected as the primary carrier plane for the Kinzhal hypersonic missile.
