page_title: Missile defense
section_title: History
hierarchical_section_title: Missile defense / History
caption_attribution_description: Deutsch: Interkontinentalraketen verschiedener Typen (Intercontinental ballistic missile, kurz ICBM) im Vergleich. English: ICBM (Intercontinental ballistic missile) Comparison.
context_page_description: Missile defense is a system, weapon, or technology involved in the detection, tracking, interception, and destruction of attacking missiles. Originally conceived as a defense against nuclear-armed intercontinental ballistic missiles, its application has broadened to include shorter-ranged non-nuclear tactical and theater missiles.
  The United States, Russia, China, India, Israel, France, and Taiwan have all developed such air defense systems. In the United States, missile defense was originally the responsibility of the U.S. Army. The U.S. Missile Defense Agency has developed maritime systems and command and control that will eventually be transferred to the Navy and Air Force for operation and sustainment.
context_section_description: In the 1950s and 1960s, Missile Defense meant defense against strategic (usually nuclear-armed) missiles. The technology mostly centered around detecting offensive launch events and tracking inbound ballistic missiles, but with limited ability to actually defend against the missile. The Soviet Union achieved the first nonnuclear intercept of a ballistic missile warhead by a missile at the Sary Shagan antiballistic missile defense test range on 4 March 1961.
  Throughout the 1950s and 1960s, the United States Project Nike air defense program focused initially on targeting hostile bombers before shifting focus to targeting ballistic missiles. In the 1950s, the first United States anti-ballistic missile system was the Nike Hercules, which had the ability to intercept incoming short-range ballistic missiles, but not intermediate-range ballistic missiles (IRBMs) or ICBMs. This was followed by the Nike Zeus, which was capable of intercepting ICBMs by using a nuclear warhead, upgraded radar systems, faster computers, and control systems that were more effective in the upper atmosphere. However it was feared the missile's electronics may be vulnerable to x-rays from a nuclear detonation in space. A program was started to devise methods of hardening weapons from radiation damage. By the early 1960s the Nike Zeus was the first anti-ballistic missile to achieve hit-to-kill (physically colliding with the incoming warhead).
  In 1963, Secretary of Defense Robert McNamara diverted funds from the Zeus missile program, and instead directed that funding to the development of the Nike-X system, which utilized the high-speed, short-range Sprint missile. These missiles were meant to intercept incoming warheads after they had descended from space and were only seconds from their targets. To accomplish this, Nike-X required advances in missile design to make the Sprint missile quick enough to intercept incoming warheads in time. The system also included advanced active electronically scanned array radar systems and a powerful computer complex.
  During the development of Nike-X, controversy over the effectiveness of anti-ballistic missile systems became more prominent. Critiques of the Nike-X included an estimate that the anti-ballistic missile system could be defeated by Soviets manufacturing more ICBMs, and the cost of those additional ICBMs needed to defeat Nike-X would also cost less than what the United States would spend on implementing Nike-X. Additionally, McNamara reported that a ballistic missile system would save American lives at the cost of approximately $700 per life, compared to a shelter system that could save lives at a lower cost of approximately $40 per life. As a result of these estimations, McNamara opposed implementation of Nike-X due to the high costs associated with construction and perceived poor cost-effectiveness of the system, and instead expressed support for pursuing arms limitations agreements with the Soviets. After the Chinese government detonated their first hydrogen bomb during Test No. 6. in 1967, McNamara modified the Nike-X program into a program called Sentinel. This program's goal was to protect major U.S. cities from a limited ICBM attack, especially on one from China.
  This would be done by building fifteen sites across the continental US, and one site in each of Alaska and Hawaii. This in turn reduced tensions with the Soviet Union, which retained the offensive capability to overwhelm any U.S. defense. McNamara favored this approach as deploying the Sentinel program was less costly than a fully implemented Nike-X program, and would reduce Congressional pressures to implement an ABM system. In the months following the announcements regarding the Sentinel program, Secretary of Defense Robert McNamara stated: "Let me emphasize—and I cannot do so too strongly—that our decision to go ahead with a limited ABM deployment in no way indicates that we feel an agreement with the Soviet Union on the limitation of strategic nuclear offensive and defensive forces is in any way less urgent or desirable."
  The Soviet Union 
caption: Various ICBMs utilized by varying countries.
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