The Sprint was a two-stage, solid-fuel anti-ballistic missile, armed with a W66 enhanced radiation thermonuclear warhead. It was designed as the short-range high-speed counterpart to the longer-range LIM-49 Spartan as part of the Sentinel program. Sentinel never became operational, but the technology was deployed briefly in a downsized version called the Safeguard program. The Sprint, like the Spartan, was in operational service for only a few months in the Safeguard program, from October 1975 to early 1976. A combination of high costs, congressional opposition, and questionable efficacy resulted in a very short operational period.