Strategic Defense Initiative
The Strategic Defense Initiative or SDI, which is also commonly called Star Wars (at first by detractors), was a proposal by U.S. President Ronald Reagan in 1983 to build a ground based and space based system to protect the U.S. from nuclear ballistic missiles. The system was never fully set up, but the research from this paved the way for the anti-ballistic missile systems of today[Citation Needed].
Goals of SDI
The basic goal of SDI was to intercept and destroy incoming nuclear ballistic missiles to prevent detonation over the U.S. In some scenarios, not all warheads would be intercepted, but enough would be to render [[[Mutually Assured Destruction|mutually assured destruction]] moot. In the scenario of "partial protection", the U.S. would be immune from complete destruction, which would deter the USSR from launching a first strike. See Game Theory and Mutually Assured Destruction.
Components of SDI
There are a limited number of ways to prevent a ballistic missile from detonating over one's territory. A brief primer on nuclear attack will help explain the problems to be solved.
The Problems
Missiles with nuclear payloads are launched in two primary ways: as ground based intercontinental ballistic missiles, and as shorter range missiles, such as submarine-launched ballistic missiles and submarine-launched cruise missiles.
- ICBMs are launched from the ground, travel into space, and return with the assistance of gravity. Most contain "multiple independently targeted reentry vehicles" or MIRVs. This means that a single ICBM can cause many nuclear warheads to detonate over multiple targets. Problems involved include detecting the launch, and deciding on what level to intercept the target. If the target is disabled before deployment of MIRVs, this obviously solves many problems. Once MIRVs are deployed, many more targets must be eliminated.
