Premise: The R-33 (Russian: Вымпел Р-33 , NATO reporting name: AA-9 Amos) is a long-range air-to-air missile developed by the Vympel. It is the primary armament of the MiG-31 interceptor, intended to attack large high-speed targets such as the SR-71 Blackbird, the B-1 Lancer bomber, and the B-52 Stratofortress.
Hypothesis: It was only intended to go for the SR-71