On this date, Sept. 28, 1975, the Safeguard system reached full operational capability, or FOC and "[gave] the United States its only defense against ballistic missile attack."

Safeguard FOC was in fact achieved three days ahead of the date scheduled years earlier when the deployment process began. This was no small feat as they established this extensive complex on the plains and wheat fields of North Dakota in 1970. The magnitude of this accomplishment, however, was overshadowed amidst the congressional debate to deactivate the program, an argument which would ultimately triumph.

Described as "one of the most complex and advanced weapons systems in the world" and a "Buck Rogers marvel," the Safeguard Ballistic Missile Defense system was composed of two nuclear-hardened phased array radars and five missile fields in North Dakota and the Ballistic Missile Defense Center in the North American Air Defense, or NORAD, Cheyenne Mountain Complex in Colorado.

The Safeguard Command, which manned the facility, was under the operational command of the Aerospace Defense Command.

The Perimeter Acquisition Radar, or PAR, is a 128-foot high nuclear hardened facility composed of reinforced concrete with 17 million pounds of steel reinforcing bars and 58,000 cubic yards of concrete and an antenna wall which incorporated 6888 antenna elements.

The PAR phased array radar, which operated at a UHF frequency, was designed to operate in a hostile-environment conducting long-range surveillance, detection and tracking of intercontinental ballistic missiles for the Safeguard interceptors. This detection and target trajectory data was then transmitted to the Missile Data Center.

Often referred to as the pyramid on the prairie, the Missile Site Radar, or MSR, was part of the Missile Site Control Building which also housed the Missile Site Data Processor. This nuclear hardened facility measured 230 feet square and 123 feet high and was equipped with four radar faces (13 feet in diameter with approximately 5,000 elements), the MSR operated in the S-band.

While the MSR could conduct surveillance with limited discrimination, it was primarily designed to track reentry targets, and track and guide the interceptor missiles to their targets. The control building connected the North Dakota Safeguard complex to the Ballistic Missile Defense Center and NORAD headquarters in Colorado Springs, Colorado.

The Safeguard system employed a layered defense with two types of interceptors. The long-range Spartan missile evolved from the earlier Nike-Zeus interceptor. Launched from an underground silo, the Spartan was a nuclear armed, three-stage interceptor, designed to intercept ballistic missile targets with a large payload in the exo-atmosphere. There were 30 Spartan interceptors deployed at the MSR site.

The Sprint missile meanwhile was a nuclear-armed, two-stage missile developed for short-range intercepts within the atmosphere. With a specially designed propellants and an underground launch station that would vertically eject the missile, the conically-shaped Sprint could achieve exceptional speeds. Seventy Sprint missiles would be deployed at the MSR and at four remote Sprint launch sites in North Dakota.

To achieve FOC both of the massive radars -- the PAR and the MSR -- had been individually tested and certified. These radars were then netted electronically with the Ballistic Missile Defense Center, or BMDC, in Colorado.

Beginning in April 1975, with this initial operational capability, the Safeguard program initiated the Safeguard Operational Experience Program. It was structured to gain data on all facets of Safeguard operations, e.g. software management, command/control/communications procedures, nuclear surety and contractor maintenance.

In August 1975, the two Safeguard radars and the BMDC participated in Vigilant Overview 76-1, a NORAD operational exercise. This successful test confirmed the command links from the NORAD Combat Operations Center through the BMDC to the Missile Direction Center within the Missile Site Control Building.

The next phase was to install the 100 interceptors. Sprint contractors completed installation on June 6, 1975, while the final Spartan contractors installed the last missile in August.

Operation "Green Mittens" under which the tactical warheads were moved to the site was successfully completed on Aug. 23, 1975. Safeguard Command military crews installed the 30th Spartan and the 70th Sprint on Sept. 17 and 18, following a Department of the Army Technical Proficiency Inspection.

The inspection, conducted Sept. 15-24, awarded the Safeguard Command a satisfactory rating and received a Department of the Army nuclear certification. As reported in the history, routine operation began then on Sept. 28 with a workforce of 450 military personnel, 170 Army civilians and 1,300 contractors, making the Safeguard system the first ballistic missile defense system deployed in the western world.

The fully operational Safeguard system was however short lived. In the summer of 1973, Secretary of Defense James Schlesinger had told the Army to plan to reduce the operational capability of the system during fiscal year 1977.

Based on this directive, the Army had planned to operate the Safeguard at full operations at least through the end of the fiscal year. For that year, Safeguard would be as "a base for obtaining experience with installation, test, and operation of a deployed BMD site."

In the interim, a variety of options were explored to maintain a reduced or limited operations. The issue was made moot as the House Appropriations Committee recommended the deactivation of Safeguard on the same day that Safeguard achieved FOC.

By November both the House and the Senate had voted to terminate the system. President Gerald Ford signed the final appropriations bill into law on Feb. 9, 1976 and on Feb. 10, the Safeguard BMD mission was formally terminated.

Nevertheless, during its short period of operation, April 1975-February 1976, the Safeguard system continued to meet all scheduled milestones and system performance was rated reliable and within design specifications.