The RSD-10 Pioneer (Russian: ракета средней дальности (РСД, tr.:RSD) «Пионер»; English: Medium-Range Missile "Pioneer") was a medium-range ballistic missile with a nuclear warhead deployed by the Soviet Union from 1976 to 1988. It carried GRAU designation 15Zh45. Its NATO reporting name was SS-20 Saber. It was withdrawn from service under the Intermediate-Range Nuclear Forces Treaty.
The missile was 16.5 m high, 1.79 m in diameter and weighed 37.1 tons. It was based on two solid-fuel fibre-glass clad stages of the RT-21 Temp 2S (SS-16 Sinner) so it was also known as the RT-21M Pioneer. The missile's range was from 600 to 5,000 km initially; the final model had a maximum range of possibly 7,500 km. Initially the missile was fitted with a single 1 MT, 1.6 ton warhead, later models could take one warhead or two and from 1980 three MIRV'd 150 KT devices (Pioneer UTTH). The CEP was also reduced from 550 metres to 150-450 meters.
It was intended to replace, or augment, the R-12 Dvina (SS-4 Sandal) and R-14 Chusovaya (SS-5 Skean) missiles deployed from 1958 and 1961 respectively in the USSR and Warsaw Pact states. It entered the development stage in 1966 and a design concept was approved in 1968 and the task given to the Moscow Institute of Thermal Technology and Alexander Nadiradze. Flight testing began in 1974 and deployment commenced on March 11, 1976, with the first supplied units becoming operational in August of that year. Up to 1986 a total of 48 launch sites, including a site at Pavschino, were equipped with 405 RSD-10 missiles.
