Spartan missile pre-launch. The Spartan, designation LIM-49A, was a United States Army anti-ballistic missile. It was a three-stage, solid-fuel surface-to-air missile that carried a thermonuclear warhead to intercept incoming warheads at high altitude. The missile was launched from an underground silo, and radio command guided. The warhead was designed to destroy incoming nuclear weapons by neutron flux rather than by blast. This very kill mechanism was, however, a major cause contributing to the phase-out of nuclear-warheads in antiaircraft and anti-ballistic missile rockets - a high-altitude nuclear explosion produced a strong electromagnetic pulse (EMP) that would destroy unhardened (i.e. unshielded) electronic devices, especially those working on the solid state component base, like transistors, integrated circuits etc. The higher integration and subtler the parts, the more damage from the EMP-induced currents in the circuitry would occur, causing damage to computers, data and communication networks, power-generating plants and grids, air traffic control systems, etc. The Spartan missile was in operational service for only a few months, from October 1975 to early 1976. A combination of high costs and the SALT I treaties made the missiles an unattractive bargain.