Following World War II, a new threat emerged from the Cold War rivalry between the U.S. and the nuclear-capable Soviet Union. The first U.S. response was to field bombers capable of delivering atomic and later hydrogen bombs against targets in Soviet territory, thereby deterring Soviet ambitions. Later, U.S. defense evolved to encompass the "Strategic Triad" approach, a highly-survivable trio of nuclear delivery options including bombers, intercontinental ballistic missiles, and submarine-launched ballistic missiles. This deterrent assured that no first strike could eliminate the U.S. retaliatory capability and created a stable world order that endured until the rise of terrorist organizations in the late 20th century.
Inter-Continental Ballistic Missiles (ICBM) were the land based component of the U.S. nuclear deterrent from the late 1950s to the present time. An ICBM is launched from a hardened underground silo, spends a few minutes in powered flight, then coasts to its target objective along a pre-determined ballistic trajectory, carrying nuclear weapons of a megaton or more yield. No ICBM was ever launched under actual war conditions, but tests showed amazing accuracy was possible, making the deterrent highly credible to potential enemies of the United States.
More than 1,000 U.S. land-based ICBMs were ready for launch by 1965.
Chart of Typical ICBM Trajectory Profile.
Atlas Inter-Continental Ballistic Missile (ICBM)
The first generation of ICBMs were slow-reacting, liquid-fueled, multistage units that were highly unreliable compared to what was to be developed later. The Atlas rocket was developed by the U.S. Air Force as the first U.S. ICBM, capable of boosting a nuclear warhead to any target on earth. The program began in the early 1950s with the first successful launch in December 1957. The liquid-fueled Atlas served as one of the primary ballistic missiles until it was phased out of strategic missile service in 1965.
After the end of its services as a strategic ICBM, Atlas missiles were refurbished and over 500 of them were used as boosters for satellite launches and other non-ICBM missions for the USAF, NASA, and other agencies. The photo to the right shows the launch of an Atlas F, the last, most improved version of the Atlas ICBM.
Titan II Inter-Continental Ballistic Missile (ICBM)
The Titan was a spin-off of the Atlas program. Titan II weapon system was first activated in 1962 and was operated in parallel with the build up of the Minuteman program. There were six squadrons of Titan II missiles, each with nine missiles, located near SAC bases. The Titan II introduced the idea of underground launch control centers and missiles fired from hardened silos. The two-stage, liquid fuel missile was nearly 100 feet long. The Mk-6 re-entry vehicle installed on the Titan II ICBM contained a W53 warhead, basically the same as the Mk-53 (B53) nuclear bomb.
As a result of arms and nuclear reduction treaties, the Titan II weapon system was de-activated in the mid 80's.
The Minuteman LGM-30G weapon system was conceived in the late 1950s and deployed starting in the early 1960s, with the 1000th Minuteman deployed in May 1967. It is a solid fueled, three-stage system, a quick-reacting, inertially guided, highly survivable component of America's nuclear Triad. Over the decades the Minuteman system has been continually upgraded with system improvements to keep pace with technical innovation allowing expanded targeting options, improved accuracy and survivability. (Photo, top of page)
At peak over 1000 Minutemen were on station. Now, about 500 Minuteman missiles are dispersed in hardened silos to protect against attack and connected to an underground launch control center through a system of hardened cables. Launch crews, consisting of two officers, perform around-the-clock alert in the launch control center. Multiple communication systems provide the President and Secretary of Defense with highly reliable, direct contact with each Minuteman launch crew. Specially configured E-6B airborne launch control center aircraft automatically assume command and control if the primary communication is lost, to ensure orders are relayed as intended.
The Peacekeeper missile is America's newest intercontinental ballistic missile, and it forms the core of the ICBM modernization program. The first test flight of the Peacekeeper was 17 June 1983, from Vandenberg Air Force Base, CA. The missile traveled 4,190 miles before dropping six unarmed test re-entry vehicles on planned target sites in the Kwajalein Missile Test Range in the Pacific Ocean. (Peacekeeper is capable of 10 independently targeted warheads.) Test flights were conducted from above-ground canisters and from Minuteman test silos reconfigured to simulate operational Peacekeeper sites. The Air Force achieved full operational capability December 1988 with the establishment of a squadron of 50 missiles.
Peacekeeper deployment fulfilled a key goal of the strategic modernization program and increased strength and credibility to the ground-based leg of the U.S. strategic Triad. With the end of the Cold War, the U.S. began to revise its strategic policy and agreed to eliminate the multiple re-entry vehicle Peacekeeper ICBMs by the year 2003, as part of the Strategic Arms Reduction Treaty II.
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