Safeguard Program

The Safeguard Program was an anti-ballistic missile system built by Western Electric and Bell Laboratories and operated by the United States Army. Safeguard entered brief service in 1975. It was designed to protect U.S. ICBM sites from counterforce attack, thus preserving the option of a retaliatory second strike. The only operational deployment of Safeguard was the Stanley R. Mickelsen Safeguard Complex, North Dakota.

Even before the complex had reached full operational capability the Department of Defense had determined that the state of readiness of the facility would be reduced by July of 1976, after a period of operational testing. The House Appropriations Committee, however, proposed that it be shut down entirely by that date. The committee reasoned that Soviet missiles armed with multiple warheads would overwhelm the system.

Safeguard used much of the same technology as the earlier Sentinel Program, which had been designed to protect U.S. cities. Sentinel was developed but never deployed. The LIM-49 Spartan interceptor used in the program was an evolution of Bell's LIM-49 Nike Zeus. Safeguard was planned for several sites within the United States, but only one was completed. Until the Ground-Based Midcourse Defense system was deployed, the Safeguard Complex was the only operational anti-ballistic missile system deployed by the United States.

The Russian counterpart to the Safeguard system was the Soviet A-35 anti-ballistic missile system, which defended Moscow and nearby missile fields. The Russian anti-missile-system remains in operation today as the upgraded A-135 anti-ballistic missile system.

Operation
Safeguard was a two-layer defense system. The long-range Spartan missile would attempt interception outside the Earth's atmosphere. The missile's long range allowed protection of a large geographic area. If the Spartan failed to intercept the incoming offensive missile, the high performance & high speed (but short range) Sprint missile would attempt an interception within the atmosphere. Both missiles used nuclear warheads, and they relied on destroying or damaging the incoming warhead with radiation rather than heat or blast. The Spartan carried a weapon with a 5 megaton yield; the Sprint in the kiloton range.

The envisioned sequence was as follows: first detection of enemy launch by Defense Support Program satellites, which sense the hot infrared exhaust of the ICBM booster. Then while in the mid-course phase, the Ballistic Missile Early Warning System radars in the far north would detect the incoming warheads. As the warheads approached (but while still in outer space) the Safeguard long-range radar (called the Perimeter Acquisition Radar, or PAR) would detect them, providing filtered information to the shorter-range and more precise Missile Site Radar (MSR). While the incoming warhead came within range of the MSR, the associated computer systems would calculate intercept trajectories and launch times.

Original deployment plan
Plans were made in the late 1960s to deploy Safeguard systems in three locations, Whiteman AFB, Missouri, Malmstrom AFB, Montana, and Grand Forks AFB, North Dakota, to protect important strategic weapons assets. However the Whiteman AFB location was canceled despite the fact that specific missile and radar site locations had already been selected. Construction was actually commenced at the North Dakota and Montana sites, but only the North Dakota site was completed. Remnants of the incomplete PAR system still remain in rural Montana.

Components
The Safeguard system consisted of several primary components, the Perimeter Acquisition Radar, the Missile Site Radar, the Spartan missile launchers, co-located Sprint missile launchers, and Remote Sprint missile launchers.

Perimeter Acquisition Radar (PAR)
The PAR was a large phased array radar that was intended to detect incoming ballistic missile warheads as they crossed over the North Pole region. Potential targets detected by the PAR would be sent to the Missile Site Radar (MSR) and to North American Aerospace Defense Command. Two radar sites were intended to be constructed on the northern border of the United States, one in Montana and one in North Dakota. Construction was begun at both locations, but because of the ratification of the Anti-Ballistic Missile Treaty, only the site at North Dakota was completed. The site, near Cavalier, North Dakota, is now operated by the United States Air Force as Cavalier Air Force Station.

Missile Site Radar (MSR)
The Missile Site Radar was the control of the Safeguard system. It housed the computers and a phased array radar necessary to track and hit back at incoming ICBM warheads. The radar building itself is a pyramid structure several stories tall. Construction was begun in both Montana and North Dakota, but only the North Dakota site remains standing. The MSR complex included the Spartan missile and some Sprint missile launchers.

Incomplete sites
Remnants of the Montana PAR site are located east of Conrad, Montana, at 48.28773°N, -111.34233°W. The remnants of the Montana Missile Site Radar were dismantled and buried. It was possibly located at 48.14049°N, -111.75727°W.

In Massachusetts, the Sharpner's Pond Anti-Ballistic Missile Site consists of the foundation of a planned radar structure.