The Scud is a mobile, Russian-made, short-range, tactical ballistic surface-to-surface (hence the nomenclature abbreviation SS) missile system. The SCUD-series guided missiles are single-stage, short-range ballistic missiles using storable liquid propellants. The Scud is derived from the World War II-era German V-2 rocket. Unlike the FROG series of unguided missiles, the SCUDs have movable fins. Warheads can be HE, chemical, or nuclear, and the missile, launched vertically from a small platform, has a range of 300 km. Unsophisticated gyroscopes guided the missile only during powered flight - which lasts about 80 seconds. Once the rocket motor shut down, the entire missile with the warhead attached coasted unguided to the target area. Consequently, Scuds had notoriously poor accuracy, and the farther they flew, the more inaccurate they became. SCUD missiles are found in SSM (SCUD) brigades at front/army level. The SCUD series of missiles gave the Soviet front and army commanders an integral nuclear weapons capability. Non-nuclear variants of the SCUD missiles have been exported to both Warsaw Pact and non-Warsaw Pact nations.