Dispite its technological advancements, the Department of Defense terminated Zeus development in 1963. The Zeus system, which cost an estimated $15 billion, suffered from several technical flaws, including an inability to distinguisd enemy warheads from chaff, reflectors, and other types of decoys.57 Still, the Army continued to develop an anti-ICBM weapon system -- referred to as "Nike-X" -- that was largely based on the technological advances of the Zeus system. Nike-X featured phase-array radars, computer advances, and a missile tolerant of skin temperatures three times those of the Zeus. In September 1967, the Department of Defense announced the deployment of the Sentinel antiballistic missile system, major elements drawn from Nike-X development. In March 1969, the Army deployed the Safeguard program, which was designed to defend Minuteman missiles, and which also was based on the Nike-X system.