The day Soviet's realized a Mikoyan-Gurevich MiG-25 was missing, Defection of Viktor Belenko.

The development of a brand-new, cutting-edge supersonic bomber by the Americans, which could effectively render the whole Soviet Air Force and air defence system obsolete, was discovered by Soviet intelligence in the late 1950s. The nuclear-armed North American XB-70 Valkyrie would travel at an altitude of 75,000 feet and more than three times the speed of sound. A small number of XB-70s would be sufficient to completely destroy any target.

The Soviet Union would only have a few years to counter the threat by developing a new interceptor that could rival the XB-70's extraordinary capabilities. But the interceptor would need to be promptly developed and mass built in order to protect the vast Soviet Union airspace.

The Mikoyan-Gurevich MiG-25, an interceptor designed to climb, catch, and bring down the American bomber, would be the outcome. But in the end, the jet would rank among the most misunderstood ones produced during the Cold War.