In February 1973, State Rocket Center Makayev began development of a new two-stage liquid-fueled ballistic missile R-29R (3M40, RSM-50, SS-N-18). Improvements in the R-29R over the original R-29 include MIRVed capability and upgraded inertial navigation system with satellite-assisted navigation, giving the new missile greater accuracy (~), increasing its damage potential against all types of military targets whether "soft" or "hard." Fire control for the R-29R is achieved through the D-9R ballistic missile system, which contains sixteen SLBM tubes, just like the preceding Project 667BD. The Delta III class most often carried 16 of the R-29R (height: ; diameter: ; starting weight: 36.3 tons) missiles each carrying 3 MIRVs (0.2 мт each) with a range of about . They also can carry R-29RK with 7 (0.1 мт) MIRVs and range of about 6,500 km or R-29RL with single (0.45 мт) warhead and range of about . Coupled with the R-29R's capabilities and the performance of the D-9R, the Russian Navy possesses, for the first time, the ability to launch any number of its missiles in a single salvo with shorter launch intervals.