 By the mid-1950s, it became obvious that subsonic cannon-armed fighters such as the Yakovlev Yak-25 would be unable to intercept fast high-altitude targets like the upcoming generation of strategic jet bombers.As a result, in 1953 Lavochkin OKB proposed addition of an air-to-air missile system to the "Berkut" air-defense system.Tasked with defense of Moscow, the "Berkut" system consisted of a large network of radars and surface-to-air missile sites as well as ground-controlled interceptor aircraft.