Papa-class

Project 661 Anchar, known to NATO as Papa, was a one-off Soviet nuclear cruise-missile submarine centered on speed, titanium construction and anti-carrier strike. K-222 was developed as a high-priority experimental platform rather than a production class. The program showed what Soviet designers could achieve with advanced materials and powerful reactors, but also exposed cost, noise and support penalties that made serial construction unattractive.

The submarine used a titanium hull, nuclear propulsion and submerged performance that made it famous as one of the fastest submarines ever built. Its main strike armament was a battery of anti-ship cruise missiles carried forward of the sail, backed by torpedo tubes. The design's speed was extraordinary, but acoustic discretion and maintainability were less favorable than later balanced submarine designs.

Operational value was limited by the fact that only one boat entered service. K-222 demonstrated sprint speed and missile-submarine possibilities, but it was too expensive and specialized to become a fleet standard. Its legacy lies in technology demonstration and lessons that influenced later Soviet submarine thinking rather than sustained combat or patrol numbers.