RSM-45 R-31 (NATO designation - SS-N-17 Snipe) was a Soviet submarine-launched ballistic missile. Development for the missile began in the early 1970s. It was fitted on only one Yankee II class submarine, originally for evaluation purposes. A first test flight took place from the Yankee II Class submarine K-140 (photo) in December 1976. The RS-16 was the first solid-fueled ICBM in the Soviet Union's strategic arsenal. It was a two-stage delivery device armed with a single 500 kt nuclear warhead. A particular practical benefit of the design was the quiet submerged launch system, which used the missile's own buoyancy to lift it to the surface.