The R-29RM Shtil (NATO designation SS-N-23 Skiff) is a liquid propellant, submarine-launched ballistic missile in use by Russia. It has the alternate Russian designations RSM-54 and 3M27. It is designed to be launched from the Russian Delta IV submarine, each of which is capable of carrying 16 missiles. The R-29RM carries four 100 kiloton warheads and has a range of about . A derivative, the R-29RMU Sineva, entered service in 2007. The last boat with R-29RM, K-51 Verkhoturye, went into overhaul for rearming with R-29RMU on 23 Aug 2010.