The RPK-2 Viyuga (Russian: РПК-2 Вьюга, meaning blizzard), also designated 81R, and identified by NATO as Starfish and the United States Department of Defense as SS-N-15, is a Russian submarine-launched, nuclear-armed anti-submarine missile system, launched exclusively through 533mm torpedo tubes.
Analogous to the now retired Subroc missile carried by US Navy submarines, it is designed to be fired from a 533 mm (21 in) torpedo tube. It is boosted by a choice of mechanisms depending on model before clearing the water, firing a solid fuel rocket and delivering its payload up to 45 km (28 mi) away. The payload ranges from a simple depth charge to a 200 kt nuclear warhead.
The RPK-2 uses a 82R torpedo or 90R nuclear depth charge in the 533 mm version, and a 83R torpedo carrying[clarification needed] or 86R nuclear depth charge in 650 mm version.
Both submarine- and surface-launched versions exist. The surface-launched versions are used by the Slava, Kirov, Neustrashimyy and Udaloy classes. The submarine-launched versions are used by the Akula, Oscar, Typhoon, Delta, Kilo, and Borei classes. However, the munition package used in either is identical and hence the ship-launched version is launched into the water and submerges before firing its engines.