During the Cold War, the US leaned heavily on the insane multi-mach speeds its SR-71 spy plane could achieve. This speed allowed it to outrun virtually every plane, anti-aircraft battery, and guided missile that the Soviets could throw at it. That is, until Moscow rolled out one of the fastest and most far-seeing planes in history: the MiG-31 Foxhound. The SR-71 had finally met its match.