The Mikoyan MiG-31 (Russian: ?????? ???-31; NATO reporting name: Foxhound) is a supersonic interceptor aircraft developed for use by the Soviet Air Forces.
For some reason the text for this post went missing after website update. Since I’m not into writing the description again, I will just copy paste what Wiki says about it.
The aircraft was designed by the Mikoyan design bureau as a replacement for the earlier MiG-25 “Foxbat”; the MiG-31 is based on, and shares design elements with the MiG-25.
The MiG-31 has the distinction of being one of the fastest combat jets in the world. It continues to be operated by the Russian Air Force and the Kazakhstan Air Force following the end of the Cold War and the collapse of the Soviet Union in late 1991.
The Russian Defence Ministry expects the MiG-31 to remain in service until at least 2030.