Minuteman III Development History
Development of the last of the series, the Minuteman III, began in December 1964. The new missile contained an improved third-stage motor with a liquid injection altitude control system and a fixed nozzle that increased the range to over 8,000 miles and significantly increased the payload. The missile was the first ICBM to be outfitted with MIRVs that enabled a single missile to carry multiple warheads, each programmed to attack a different target. The Minuteman III could carry three warheads. A liquid-fuel postboost propulsion system maneuvered the missile before deployment of the reentry vehicles. An improved guidance system with an expanded memory also improved the system accuracy; the Minuteman III warheads are said to be accurate to within 800 feet.
In February 1968 the fourth Minuteman III test vehicle fired from Vandenberg AFB completed a successful 5,500-mile flight. In January 1971 the first squadron of Minuteman IIIs was turned over to the 91st Strategic Missile Wing at Minot AFB, North Dakota. The force modernization effort continued throughout the early 1970s and by July 1975 there were 450 Minuteman IIs and 550 Minuteman IIIs under SAC's control.
Beginning in 1966 the Air Force instituted a comprehensive long-term maintenance program to ensure that the Minuteman force remained a strong and viable deterrent for years to come. In 1966 the Air Force initiated a Minuteman aging surveillance program and in 1976 began a long-range service life extension analysis for the propulsion system. The latter effort resulted in the remanufacturing of the Minuteman II second-stage motor and an investigation of the condition of the liner in the Minuteman III third stage. Also during the 1970s many of the Minuteman launch facilities were further hardened and the missiles were fitted with new command data buffers that facilitated faster retargeting. In 1985 the Air Force began the comprehensive Rivet MILE (Minuteman Integrated Life Extension) program destined to take the Minuteman force into the twenty-first century.
A further change in the Minuteman force occurred in January 1986 when the Air Force began removing 50 Minuteman IIIs from their silos at F.E. Warren AFB and began replacing them with the new Peacekeeper ICBM. When that process was completed, the nation's ICBM force stood at 450 Minuteman IIs and 500 Minuteman IIIs. It remained at that level until 1991 when President George Bush ordered all 450 Minuteman IIs taken off operational alert. The Air Force is now in the process of removing the missiles from their silos and destroying the launch facilities.