Delta class submarine

The Delta class submarine (Project 667B) has formed the backbone of the Soviet and Russian strategic submarine fleet since its introduction in 1973. They carry nuclear ballistic missiles of the R-29 Vysota family, with the Delta I,II, III and IV carrying the R-29 (SS-N-8 'Sawfly'), R-29D (SS-N-8 'Sawfly'), R-29R (SS-N-18 'Stingray') and R-29RM (SS-N-23 'Skiff') respectively. The Delta I carried 12 missiles, the Delta II was a "stretched" Delta I that could carry 16 missiles; the Delta III and IV carry 16 missiles with multiple warheads and the submarines have improved electronics and noise reduction.

The R-27 Zyb missile carried by the Yankee class submarines of the late 1960s had a range of just 2,500–3,000 km (1,550–1,860 mi), so the earlier subs were forced to patrol close to the North American coast, whereas the Deltas could launch the >7,700 km (4,780 mi)-range R-29's from the relative safety of the Arctic Ocean. In turn the Deltas were superceded by the massive Typhoon class submarines. However the Deltas remained in service until the end of the Cold War with treaties such as START I. High running costs and the retirement of the Typhoons' R-39 (SS-N-20 'Sturgeon') missiles meant that some Delta III's were reactivated in the early 2000s to replace the Typhoons in Russian service.

As of July 2008^[update], the Center for Arms Control Studies estimated the strength of the Russian strategic submarine fleet at one Typhoon class submarine (used to trial the R-30 Bulava missile), six Delta III and six Delta IV subs.^[1] Of these two Delta III boats were decommissioning, with the rest expected to follow in the next few years.^[1] They will ultimately be replaced by the new Borei class submarines, of which the first is undergoing sea trials without its missiles^[1] and is not due to enter service until 2011. Four Delta IV boats have been overhauled in recent years, with work continuing on the other two.^[1] The seventh Delta IV, K-64 Vladimir, has been converted for use by Special Forces.. more..