SS-28
On 10 August 1979 the tests of the modernized "Pioneer"-UTTKh (15Zh53) began on the Kapustin Yar test site. They continued through 14 August 1980, and on 17 December 1980 the missile designated as SS-20 Mod3 was deployed. This variant had the same propulsion system as earlier versions, but it due to upgrading of a command structure and instrumentation-service unit it was possible to improve accuracy (CEP) from 550 to 450 meters, to increase maximum range by 10 %, and to increase the area covered by the warheads.. This latest RSD-10 variant subsequently received NATO reporting name SS-28 Saber 2.
Read more about this topic: RSD-10 Pioneer