SDI

SDI

Strategic Defense Initiative (SDI), United States military research programme to develop a defence system to destroy incoming enemy missiles.

"Star Wars"

The Strategic Defense Initiative was first proposed on March 28, 1983, when President Ronald Reagan, in regretting that peoples' security rested upon "the threat of instant US retaliation to deter a Soviet attack", appealed to America's scientific community, "who gave us nuclear weapons … to give us the means of rendering these nuclear weapons impotent and obsolete". Reagan's vision was the deployment of such effective ballistic missile defences that the whole populations of the United States, America's Western European allies, Canada, and Japan would be protected from an all-out nuclear attack.

Such a ballistic missile defence was to involve many weapon systems in space, including a network of satellites and space battle stations, equipped with such exotic weapons as high-energy lasers, particle beams, electromagnetic rail guns, X-ray lasers, and computer-guided mini-missiles, all controlled by a space battle management system using supercomputers. President Reagan's SDI was therefore dubbed "Star Wars"-evoking space battle scenes from the famous film.

SDI was the most expensive military project in history; the estimates of the total cost range up to a trillion (million million) dollars. Despite warnings from many eminent scientists and technologists that an effective SDI was technologically impossible, about $40 billion was spent on research and development.

Background to SDI

Proposals for defending the mainland of the United States against a long-range ballistic missile attack, particularly by Soviet intercontinental ballistic missiles (ICBMs), date back at least 40 years. Soviet interest in ballistic missile defence is as long-standing. By the end of the 1950s both superpowers were replacing long-range bombers with ballistic missiles as the main element in their strategic nuclear forces. Attention therefore switched from anti-aircraft defences to ballistic missile defences.

Ballistic Missile Defence

Early proposals involved a two-layered ballistic missile defence in which enemy warheads would first be intercepted outside the Earth's atmosphere by missiles with a range of about 700 km (434 mi). Enemy warheads that survived the first layer of defence would be attacked with high-acceleration missiles within the Earth's atmosphere at ranges of up to 40 km (25 mi).

In 1975 the United States decided not to deploy an anti-ballistic missile system; since then, it has concentrated on research.

There were two reasons for this decision. Ballistic missile defences would, by defending cities, reduce the effectiveness of the policy of nuclear deterrence based on the doctrine of mutual assured destruction, which depended on holding an enemy's cities as hostages to prevent the enemy making a pre-emptive nuclear attack. The second reason was the negotiation of the 1972 treaty on the limitation of anti-ballistic missile systems (the ABM Treaty-see Arms Control and Disarmament). This treaty prohibits the deployment of ABM systems for the defence of the whole territory of the United States and the Union of Soviet Socialist Republics, but permits the deployment of ABMs around just one area in each country-either for the defence of the national capital, Washington, D.C. and Moscow, or for the defence of one ICBM silo complex each.

ABM Treaty and SALT

The ABM Treaty was meant to strengthen the policy of nuclear deterrence by mutual assured destruction, and to slow down the nuclear arms race between the two superpowers by preventing each side from reacting to the other side's deployment of ABM systems-by increasing the number of its own ICBMs in order to saturate the other side's ABM defences. The first Strategic Arms Limitation Treaty (SALT I) entered into force at the same time as the ABM Treaty. It limited the number of ICBM launchers and the number of ballistic missile launchers on modern submarines deployed by both sides, and was also meant to slow down the nuclear arms race.

Despite limiting the increase in the number of nuclear weapons in the Soviet and American arsenals, the ABM and SALT I treaties totally failed to prevent the next qualitative round in the nuclear arms race from occurring: namely, the improvement in the quality of strategic nuclear ballistic missiles by the development and deployment of multiple independently targetable re-entry vehicles (MIRVs).

The Americans decided not to deploy ABMs; after the construction of one out of four projected systems, code-named Safeguard, to protect ICBMs housed in silos at Grand Forks, North Dakota, the US Congress closed down the programme. The Soviet Union, however, deployed an ABM system of Galosh and Gazelle missiles around Moscow. It became operational in 1964 and is still in operation. One hundred ABMs are deployed, supported by early-warning radar and battle management systems.

American interest in anti-ballistic missile systems was rekindled in March 1983, when the proposals for SDI were made public by President Reagan.

With the dissolution of the Soviet Union, the signing of the START (Strategic Arms Reduction Treaty) I and II treaties, and the election in 1992 of Bill Clinton as President, SDI, like many other weapons programmes, was given a lower budgetary priority. In 1991, President George Bush had announced that the emphasis would shift from defence against attack by strategic (long-range) ballistic missiles to defence against tactical (medium-range and short-range) missiles. SDI was abandoned in favour of Theater Missile Defense (TMD), a less costly programme administered by the Ballistic Missile Defense Organization (BMDO), that would make use of ground-based anti-missile systems, including the Patriot missile system.