System for which planning began in the United States in the 1960s to guard against a nuclear attack. The concept of missile defense is a product of the Cold War, a time in which the international framework was determined by competition between the two global superpowers: the United States and the Soviet Union.
During the Cold War, both superpowers possessed overwhelming arsenals of nuclear weapons, so the prospect of nuclear war played a central role in diplomatic relations between them. The purpose of a National Missile Defense system would be to intercept nuclear missiles before they could strike the United States. Thus, the initiative was conceived as purely defensive. However, the fact that an impermeable defense umbrella would also undermine the concept of mutually assured destruction (MAD)—the idea that neither side would start a nuclear war because the consequences of retaliation were too severe—put the development of a National Missile Defense system at the center of arms negotiations in the early 1970s.
The Nike-Zeus Program, initiated in the late 1950s, introduced the ultimately unpalatable prospect of nuclear missiles being used to intercept nuclear missiles. The Nike warhead would detonate in the vicinity of the incoming Soviet intercontinental ballistic missile (ICBM), thus destroying the enemy missile. The risks to the project were obvious, and the potential countermeasures (such as decoys) were easily imaginable. The Nike-Zeus project was therefore abandoned in 1961.
U.S. Defense Secretary Robert McNamara announced the Sentinel program in 1967, in the midst of the Vietnam War. Rather than attempting to account for a general nuclear attack against the United States, the Sentinel was envisioned specifically to safeguard against a nuclear attack from China. (It was assumed that China would be capable of launching an intercontinental ballistic missile by 1970.) A secondary advantage of developing the Sentinel system is that it allowed the United States to continue arms-reduction talks with the Soviet Union because the program was not directed against it. Opposition to the Sentinel program became part of the more general protest movement at the time against the Vietnam War. The Sentinel system was ultimately abandoned and replaced with a program called Safeguard to defend ballistic missile sites in North Dakota.
The development of the Sentinel raised the problem of MAD. The possibility that a nation might feel forced to initiate a preemptive strike—realizing that after the system was in place it would have no retaliatory capability—led to the signing of the Antiballistic Missile Treaty in 1974. It also left open the question of how a defense system could be developed that would not be perceived as offensive.
The Strategic Defense Initiative (SDI), better known as Star Wars, was initiated during the administration of President Ronald Reagan as a system that would provide a space-based defense umbrella for the United States. Reagan’s stated goal was to share the technology with the Soviet Union, thus negating the question of MAD. Funding for SDI began in 1984, but the fall of the Berlin Wall and subsequent collapse of the Soviet Union in the early 1990s removed motivation for the project. Star Wars has been reinvented to serve in the war on terrorism with President George W. Bush’s National Missile Defense program.
Work on a missile defense program continued under President Bill Clinton, but with little momentum. The terrorist attacks of September 11, 2001, provided a new rationale and a new approach to the concept of missile defense. President George W. Bush announced the National Missile Defense program in 2002, soon renamed the Ground-Based Missile Defense system because the idea of ground-based interceptors seemed, at least in the short run, to be more technologically feasible. In recognition of the U.S. role as the sole remaining global superpower, the purpose of the system is projected to guard against acts of nuclear terrorism. However, the question of whether any kind of missile defense system—deployed against terrorists or another nation—could ever be effective remains controversial.
Strategic Defense Initiative (SDI)
A rocket propelled, self-guided type of strategic weapons system that can be used to perpetrate a chemical, biological, or nuclear attack. The...
Since the dawn of the nuclear age, in part because of its faith in the power of technology, the United States has been one of the leaders in...
A Cold War defense program initiated in the early 1980s by President Ronald Reagan, the Strategic Defense Initiative (SDI)—popularly referred to as