The Project 670M Skat-M (NATO: Charlie II-class) SSGN was an improved variant of the Charlie I-class Soviet nuclear-powered cruise missile submarine. Entering service in the 1970s, it featured upgraded weapons and systems for enhanced anti-ship strike capability against NATO surface fleets, particularly U.S. carrier battle groups.The Charlie II was armed with eight P-120 Malakhit (SS-N-9 Siren) cruise missiles, which had greater range and improved targeting over the P-70 Ametist missiles of its predecessor. These missiles were housed in vertical launch tubes forward of the sail, allowing for underwater launch. It also carried 533mm torpedoes for close-range engagements.With a submerged speed of 24 knots and a maximum depth of around 350 meters, the Charlie II remained an effective platform but was still considered noisier than its Western counterparts. It served as a transitional design before the introduction of the larger and more capable Oscar-class SSGNs in the 1980s. The class was retired by the 1990s, with some units transferred to the Indian Navy under lease agreements.