The R-31 was a Soviet Submarine launched, Ballistic Missile, first deployed in 1971. Designed for The ''Yankee''-Class Submarine, The R-31 was the first of it's type to use Astro-Inertial Guidance. Supporting a 500-KT warhead, The R-31 was seen by NATO Forces as a ''City Killer'' – with the purpose of being launched (submerged) against an Enemy Coastal habitation. The Missile (comparable with The US ''Polaris'' at the time), had a 2,800-mile tactical effective range. Most Soviet Ballistic Submarines at the time deployed with The R-31 BM. They were decommissioned by The Soviet Navy in 1991.