The Safeguard system consisted of three major subsystems: missiles, radars, and data processing and control. Incoming inter-continental ballistic missile (ICBM) warheads, after being detected and tracked by the radars, were to be intercepted and destroyed by defensive missiles. The radars and defensive missiles were controlled by the data processing system.
Two types of interceptor missiles were used: Spartan for long range attack before the threatening ICBM warheads re-entered the atmosphere, and Sprint for short range "close in" attack of targets that survived Spartan intercept. Both used nuclear warheads to destroy their targets.
The Perimeter Acquisition Radar (PAR) site utilized a large single-face phased array radar to provide early detection and trajectory data on threatening ICBM's. Functions of this site included long range surveillance, detection, and target selection of threatening objects, and ICBM threat tracking for Spartan intercept. This last capability significantly increased the long range Spartan field of fire. The PAR site did not perform missile guidance.
The Missile Site Radar (MSR) installation used the target trajectory and classification data from the PAR along with additional data supplied by its multiface phased array radar. This site provided additional surveillance and target tracking and also performed the function of track and guidance for the Sprint and Spartan missiles.
Both PAR and MSR sites reported to the Ballistic Missile Defense Center (BMDC), a central command center. The BMDC provided a command interface with other military systems and a means of disseminating command directives and controls.
The PAR and MSR radars were controlled by the data processing systems, collocated with the radars. At the PAR and MSR sites, application programs performed surveillance, tracking, target classification, radar management and testing, intersite communication, and display functions. Additional application programs at the MSR supported the battle management and missile guidance functions. The BMDC data processing system primarily contained display and command/control programs.
Spartan launchers were located only at the MSR site. Sprint launchers were located at the MSR site and at four geographically dispersed Remote Sprint Launch (RSL) sites. The RSL's were designed (along with Sprint's ultra fast acceleration) to minimize fly out time during the short period available for Sprint intercepts.