Russia has decided to refurbish its force of 1970s era R-36M (SS-18 or "Satan" in the West) ICBMs so they can remain in service another 10-15 years. The R-36M was designed in 1969, first tested in 1972 and entered service in 1975. It's the largest ICBM the Russians ever built, with a liftoff weight of 210 tons and a warhead weighing eight tons. While it's a liquid fuel rocket, storable liquid fuel is used. This avoids lengthily fueling procedures common with earlier Russian ICBMs. Modifications and upgrades for the missile produced six separate models, the last one entering service in 1990. Russia is apparently going to refurbish 100-150 of the most recently built (in the 1980s, for the most part) missiles. These carry ten warheads, have a range of 16,000 kilometers and will put half it's 550 kiloton warheads within 500 meters of the aiming point (the other half will land up to several kilometers outside that circle.) The missile is 112 feet long, ten feet in diameter, has two stages and is fired from silos. Russia has about 200 of them left, out of about a thousand that were manufactured during the Cold War. The refurbishment, in addition to replacing any motor and missile body parts that had deteriorated over the years, will probably install a more accurate and reliable guidance system. Some R-37Ms, scheduled for destruction in compliance with disarmament treaties, are being used to launch satellites instead. Disarmament officials considered this a satisfactory form of "destruction." About 150 R-36Ms were purchased by a private firm for this. Russia's decision to keep R-36Ms in service is probably based on economic considerations, it being cheaper to refurbish an existing, and reliable, system than in developing a new system. More recent missiles than the R-36M are more expensive to build and have not been as reliable.