With a top speed approaching Mach 3 and equipped with both powerful sensors and air-to-air weaponry, the two-seater MiG-31 interceptor has proven to be one of the Cold War's most formidable survivors - finally coming into its own during the Ukraine War. Development began in 1975 with a design based on that of the MiG-25 Foxbat and progressed to the point where, although it bore a superficial similarly to its forebear, it was largely a new aircraft. The MiG-31, NATO reporting name Foxhound, entered service in 1981 and more than 500 were built. Several dozen examples remain in service today with both the Russian and Kazakh air forces - and throughout 2022 and 2023 Foxhounds using R-37M long-range AAMs operated virtually unopposed against Ukrainian fighters, which lacked the speed, range, altitude and firepower to engage them. MiG-31s have also provided a valuable platform from which to launch Kh-47M2 Kinzhal hypersonic missiles against Ukraine while remaining within Russian airspace. Author Sergio Santana details the aircraft's early development, its long operational history and its most recent operations in this all-new look at one of the world's deadliest combat aircraft.