The Air Force ballistic missile program had its origins in studies and projects initiated by the Army Air Corps immediately after World War II. These efforts aimed at mating the German V-2 ballistic missile and the atomic bomb--a union that, if realized, would completely revolutionize weaponry and strategic warfare as it then existed. Technical problems held the program back at first, but the situation was changed drastically by the so-called "thermonuclear breakthrough" of the early 1950's. This breakthrough made it possible to manufacture high-yield nuclear weapons that were small enough and light enough to be carried as warheads aboard ballistic missiles.

While these developments were taking place in the US, the Soviet Union was making significant progress in the development of thermonuclear weapons and ballistic missiles of its own. If the Soviet missile threat were real and the missiles deployed, the USSR could gain a sudden and possibly decisive strategic advantage over the US. In view of this danger, the US government decided to accelerate its missile development efforts, and the Western Development Division was established to carry out that task.

Atlas missile 25-D rises to a vertical position and begins a test flight on 22 April 1960. Atlas Ds--the first Atlas missiles to become operational--were stored in unprotected, above-ground horizontal launchers. Later models of the Atlas were better protected. Atlas Es were stored in semi-hardened horizontal launchers, and Atlas Fs were stored in hardened vertical silos.

Initially, the Western Development Division was responsible for developing just one missile--the Atlas. The Atlas, which was being designed and built by the Consolidated Vultee Aircraft Corporation (Convair), was an intercontinental ballistic missile with liquid fuel engines and a stage-and-a-half configuration. Within a year, the Division had also become responsible for developing an alternate, or backup missile called the Titan. A more advanced, two-stage missile to be built by the Martin Company, the Titan was a hedge against failure or delay in the Atlas program. By the end of 1955, the Division was given the additional task of developing an intermediate range ballistic missile, the Thor, and was also charged with achieving initial operational capability with the three missile systems it was now building. In barely 18 months, the mission of the Division had undergone an enormous expansion.

A Titan I missile emerges from its silo at Vandenberg's Operational System Test Facility in 1960. The Titan I was stored and fueled in a hardened underground silo, but an elevator had to lift it out of the silo before it could be launched. The entire launch sequence took about 15 minutes. Ultimately, the Titan I was deployed in 54 such silo-lift launchers divided among seven operational sites. All became operational in 1962, and all were inactivated in 1965.

To attain its assigned objective of developing operational missile systems as soon as possible, the Division largely replaced the conventional pattern of sequential development with concurrent development. Within the framework of a single overall plan, development, production, testing, and initial operational capability actions were undertaken simultaneously. Although the concept of concurrency was not entirely new, the Division applied it on a scale never before used in military development programs.

The development of ballistic missile systems was slowed in 1956-1957, when the Eisenhower administration made large cuts in defense spending in an effort to balance the budget. However, on October 4, 1957, the Soviet Union used an ICBM to launch Sputnik, the first man-made satellite. Sputnik's impact was immediate and dramatic. The US missile program was given renewed impetus, restrictions were lifted, previous program priorities were reinstated, and funding was vastly increased.

Thor missiles, in Royal Air Force livery, on station in England. The first Thor wing of 15 missiles was turned over just three and a half years after the inception of the Thor program.

On September 20, 1957, even before Sputnik, the Air Force Ballistic Missile Division had successfully launched a Thor missile from Cape Canaveral, Florida. On December 17, the first successful Atlas launch was made, also from Cape Canaveral. Following these successes, the Air Force missile program progressed rapidly. Deployment of the Thor was completed in 1960, while deployment of the Atlas was completed in 1962. The Titan made its first successful flight in 1959 and was deployed in 1962. By the end of 1962, therefore, all three first generation missiles were in place and ready for operation.

In the late 1950's, the Ballistic Missile Division had begun developing two second generation missiles--the Titan II and the Minuteman. Like the original Titan I, Titan II was a two-stage, liquid fuel missile. Unlike its predecessor, however, it used storable propellants and an all-inertial guidance system, and it could be launched from hardened underground silos. These improvements gave the Titan II quicker reaction time, greater survivability, and improved performance. The first Titan II unit achieved operational status in June 1963 and the last in December of the same year.

Second generation ICBMs-- the Titan II (far left), Minuteman I (center left), Minuteman II (center right), and Minuteman III (far right). Unlike the Titan I, which had to be raised to the surface before launch, the Titan II and the MInuteman could be launched directly from their underground silos.

The Minuteman was the first US intercontinental ballistic missile to use solid rather than liquid fuel. It possessed all the virtues of the Titan II, and its use of solid fuel gave it two additional advantages--greater simplicity and economy. The first Minuteman flight test missile was launched in February 1961, and the first group of Minuteman missiles was turned over to the Strategic Air Command at the end of 1962. By the end of 1965, Minuteman missiles had been deployed at four bases in the north central United States, and the older, less efficient, and less economical Atlas and Titan I missiles had been retired from the active inventory. The Minuteman, along with the Titan II, became the mainstay of the nation's strategic missile force. Together with SAC's manned bombers and the Navy's Polaris/Poseidon missile-launching submarines, these missiles formed the triad of strategic deterrent forces that were maintained on day-to-day alert to counter any hostile nuclear attack on the US or its allies.

Just as the Atlas and the Titan I had been replaced by the Titan II and the Minuteman, the original Minuteman was itself replaced by the more advanced Minuteman II and Minuteman III. The Minuteman II incorporated a new, larger second stage, improved guidance, greater range and payload capacity, and greater resistance to the effects of nuclear blasts. The Minuteman III, for its part, possessed an improved third stage, employed more penetration aids to counter anti-ballistic missile defense systems, and was equipped with up to three independently targetable warheads. By the end of 1975, 450 Minuteman II's and 550 Minuteman III's were in place and ready for operation at six bases in the north central United States.

Other portions of the ballistic missile force were becoming obsolete. The Air Force issued direction to deactivate Titan II missiles on 30 April 1982. The 55 operational missiles were removed from their silos during 1982-1987 and placed into storage for possible conversion to space launch vehicles.

Under the terms of the 1972 Strategic Arms Limitation Agreement between the United States and the Soviet Union, this country was barred from increasing the number of strategic missiles in its operational inventory. If it wished to maintain its strategic position vis-a-vis the Soviet Union, therefore, it had to do so by improving the quality of its missiles rather than by increasing the quantity. With this objective in view, an advanced development program was started in late 1973 to define the technology and design concepts for a new strategic missile called Missile X. A great deal of effort was devoted to studying alternate basing concepts for this missile, including air-mobile and ground mobile concepts.

A Peacekeeper Flight Test Missile during launch from Vandenberg AFB in June 1985. Unlike the Minuteman, which was launched by igniting the stage 1 motor while the missile was still in the silo, the Peacekeeper was ejected from its silo by hot gas, and its stage 1 motor was ignited when it was about 100 feet above the ground.

Train proposed for use with the rail-mobile version of the Peacekeeper.

Missile X was renamed the Peacekeeper by President Reagan on 22 November 1982. It was a four-stage ICBM capable of precisely delivering 10 reentry vehicles to different targets more than 6,000 miles away. It successfully carried out its first flight test in June 1983, when a Peacekeeper that had been cold-launched from a canister at Vandenberg AFB reached its target in the Kwajalein Missile Range. In April 1983, the President accepted the recommendation of the Scowcroft Commission that the Peacekeeper be temporarily based in existing Minuteman silos. The first ten missiles went on alert in December 1986, and the basing program achieved full operational capability when the fiftieth missile entered its silo in December 1988. DOD accepted a concept for a permanent basing mode in 1986. It involved placing 50 Peacekeeper missiles on 25 trains, which would be kept in protected shelters scattered throughout the country. When war threatened, the trains would be released to travel over the commercial rail network until their missiles had to be launched. The program entered full-scale development in May 1988. By the early 1990s, however, the Cold War was winding down, and the Soviet threat was diminishing. In a dramatic speech delivered in September 1991, President Bush announced a wide-ranging plan to unilaterally reduce the American nuclear arsenal and eliminate several categories of weapons. As part of the plan, he announced the cancellation of the Peacekeeper Rail Garrison program.

The Scowcroft Commission had also recommended the development of a new, lightweight missile carrying only one reentry vehicle. President Reagan authorized full-scale development of the Small ICBM (SICBM) in December 1986. SICBMs would be housed in mobile launchers based at widespread locations. When hostilities threatened, the launchers would drive out onto the roadways and scatter across the country. The program narrowly escaped termination in 1988 because of reduced funding. It achieved its first totally successful flight test in April 1991, when a SICBM that had been cold-launched from a canister at Vandenberg AFB reached its target in the Kwajalein Test Range. Nevertheless, President Bush canceled the SICBM program in January 1992. Like the Peacekeeper Rail Garrison program, the SICBM program was no longer needed in the post-Cold War environment.

A simulated Small ICBM being ejected from its launch canister in the Canister Assembly Launch Test Program (CALTP). Like the Peacekeeper, the Small ICBM was to be "cold launched"; i.e., the missile was to be ejected from a canister and its stage 1 motor was to be ignited after the missile was in mid-air. The CALTP program tested the launch eject system and the effects of a cold launch on stage 1 of the missile.

A mobility test vehicle-- forerunner of the hard mobile launcher that would have transported and launched the Small ICBM if it had become operational.