On August 22nd a retired Russian ICBM launched a South Korean satellite into orbit. This was a 1.4 ton KOMPSAT 5 satellite that uses a radar that can detect objects and landforms as small as one meter (39 inches) across. This satellite is mainly for obtaining geographic (land and sea) information and supporting disaster response and environmental monitoring. While the satellite was new tech, the launcher was 1970s technology that was affordable and reliable.
Russia still has about 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. The 106 ton, 24.5 meter (76 foot) long RS-18 uses storable liquid fuel, meaning that the missile is inherently more complex to maintain than a solid fuel missile. Thus the older engines, and other components, of the first RS-18s to enter service are expensive to maintain but still in good shape to launch. Instead of nuclear warheads, the retired RS-18s are putting satellites into orbit before their engines become too old to be reliable. So far 17 of 18 RS-18s used as satellite launchers were successful. That’s a success rate of 94 percent, which by any standard is exceptional. More importantly, liquid fuel rockets can lift a heavier load than solid fuel rockets so the last generation of Russian liquid fuel ICBMs (the RS-18 and RS-20) are superior as satellite launchers than American ICBMs (which since the 1980s have all been solid fuel). The last liquid fuel American ICBM, the Titan, was also converted to be a satellite launcher and many were later built just for that. The last of these was used in 2003.
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 (the 45 ton RS-12M). The last RS-18s were manufactured in 1990, and Russia expects each of them to have a useful life of 30 years via the equipment improvements and careful maintenance. Older ones will often end up being used for satellite launches rather than scrap.
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, Independent Reentry Vehicles, which means each of six warheads in the missile had its own guidance system). The SS-19 carries six warheads. The RS-18 ICBM had a range of 10,000 kilometers. The RS-18 is converted into a satellite launcher by adding a third stage. Such missiles can lift 1.8 tons into orbit. Current technology enables small satellites (as small as 100 kg/220 pounds or less) to do useful work, and some RS-18 satellite launchers have carried many of these at once.
The heavier (217 ton) RS-20 ICBMs have a max satellite payload of nearly three tons. Russia could also use these older ICBMs to quickly launch mini-satellites, although they are not working on this at the moment, as there are only 40 RS-20s still in service. These are expected to reach the end of their useful lives as ICBMs by the end of the decade and it may be cost effective to design a third stage for them so they can be used as satellite launchers.