In the mid-1950s a major threat was a Soviet nuclear attack carried out with the Tu-4 (a B-29 clone). Up to then U.S. fighters had been equipped with either 20mm cannons or 12.7mm machine guns, and unguided rockets like the Mk 4 FFAR. None of these were effective at shooting down aircraft, especially not high speed bombers, and true air-to-air missiles were still in their infancy. Thus, a solution was found in the AIR-2, as it was nuclear armed it could be fired into a bomber stream, and when detonated could bring a number of bombers in one detonation. The AIR-2 was only live-fired once, during the Plumbbob John nuclear test over Yucca Flats, at an altitude of 4.5km. The warhead had a yield of 1.7 kilotons.
Video of the test can be seen from 6:00 to 6:30.
In the end the Genie was maintained through the 80s, and would have been at the frontline of any Soviet air attack against North America. It's effectiveness is debatable against bombers like the Tu-160 or Tu-22M, but it would have been highly effective against the Tu-95.