Deployment
Arguably, the Warsaw Pact enjoyed in Central Europe a massive conventional superiority over NATO. Soviet leaders assumed that NATO would use Theater Nuclear Forces to stop a massive Warsaw Pact offensive. The RSD-10 provided the Soviet Union with an in-theater "selective" targeting capability that it previously had lacked. The RSD-10 had the capacity to destroy all NATO bases and installations with negligible warning. Thus, the Soviet Union acquired the capability to neutralise NATO's tactical nuclear forces with surgical nuclear strikes.
In 1979 NATO decided to deploy US Pershing II and Tomahawk missiles in Western Europe in attempt to counter the RSD-10. In 1979, when the NATO decision was taken, the Soviet Union had 14 (1 operational) SS-20 launch sites.
Read more about this topic: RSD-10 Pioneer