On August 22nd Russia conducted another successful test of its RS-12M (RS-24/
Topol-M) ICBM. While this is an older (late 1980s) ballistic missile design it is still in service. Only about a hundred were built and 72 are installed in silos. As is Russian (and American) custom some silo based ICBMs are periodically fired for quality control purposes. The Russians used to fire the test missiles from their actual combat silos but now follow the American method of moving the missile to a test launch site. In this case it was Kapustin Yar in southern Russia. The RS-12M test sent the missile 10,000 kilometers to a missile testing site rented in Kazakhstan. The test warhead his its target area.
Originally the RS-12M ICBM was going to replace hundreds of older liquid-fueled ICBMs. But the end of the Cold War in 1991 and the sharp cuts in defense spending wrecked that plan. Since then an upgraded version of the RS-12M ICBM was developed and this one is replacing those older Cold War era ICBMs. Russia believes RS-24 is a worthy successor to the venerable, reliable and aging RS-18s. Reinforcing that attitude is a string of successful RS-24 test firings. Russia began deploying RS-24s in 2010. In 2013 the program to replace RS-18s with RS-24s accelerated, indicating a high degree of confidence in the RS-24 and enough cash to retire the RS-18s and build RS-24s to replace them. The 106 ton RS-18 is a 24.5 meter (76 foot) long missile that uses storable liquid fuel, meaning that the missile is inherently more complex than a solid fuel missile. But that also means you don’t require hours of preparation to fuel the missile. The RS-18 entered service in 1975, and it wasn't until the 1980s that Russia began producing reliable solid fuel rocket motors large enough for ICBMs like the 45 ton RS-12M. The last RS-18s were manufactured in 1990 and Russia expects each RS-18 to last 30 years if well maintained, regularly refurbished and needed badly enough.
The RS-18 was developed as a "light" ICBM, in effect, a competitor for the U.S. Minuteman series. The RS-18 was the first Russian ICBM to carry MIRV (multiple independently targeted reentry vehicles). The current RS-18 carries six warheads and has a range of 10,000 kilometers. RS-12M has a max range of 11,000 kilometers. Russia is also extending the life of its heavier (217 ton) RS-20 ICBMs to 30 years. This missile carries ten warheads and is also being converted to launch satellites. Eventually RS-12M will probably replace this one as well.
In 2009 Russia announced that the latest version of the Topol series, the RS-24, had entered service. The RS-24 appears to be a slightly heavier version of the 46 ton RS-12M1/M2. The RS-24 is being deployed in silos as well as on wheeled vehicles. The RS-24 carried more warheads (up to ten) than the Topol-M. The Russians developed the RS-24 to enable them to use all the additional warheads to penetrate American missile defenses.
At one point Russia planned to develop a liquid-fuel ICBM to replace its RS-18 and RS-20 (SS-18) ICBMs. The prototype was built but not tested. Russia had also announced plans to replace the old liquid-fuel missiles with the Topol M and this plan is apparently being implemented with the RS-24. This depends on being able to avoid cut to the defense budget despite sanctions and low oil prices. As Russia learned in the 1980s, economic fundamentals win in the end. The Soviet Union dissolved in large part because it was broke.
It was never explained why Russia is sticking with liquid-fuel technology for the Cold War era “heavy” missiles. It might have something to do with the liquid-fuel missiles being able to lift heavier loads, making it possible to use them to also launch satellites. The liquid fueled missiles weighed 100-220 tons and had warhead weights of 5-9 tons. In contrast, all American ICBMs (including those launched from subs) are solid fueled and have a warhead weight similar to the RS-12M (about a ton). Russian SLBMs (Sea Launched ICBMs) also have the one ton warhead.
Russia continues to test launch older RS-18 and RS-20 ICBMs. Russia still has over a hundred (out of a 1980s peak of 360) RS-18s in service and expects to keep some of them active into the next decade or until replaced by the new design. The test firings for most of the last decade have been successful, and other quality-control tests have come back positive. Despite the post-Cold War collapse of the Russian military, cash and quality personnel kept going to the missile forces, which are the final defense of the largest nation on the planet.