SDI (Strategic Defense Initiative) was launched in 1983 by US Pres Ronald Reagan to explore the possibility of protecting the USA against incoming ballistic missiles using layered ground-, sea-, air-, and space-based defences. Until then, it had been assumed, rather as it had been about bombers in the 1930s, that missiles would ‘always get through’ and anti-missile defences—to shoot incoming missiles down—had been banned under the Anti-Ballistic Missile (ABM) Treaty (see arms control). They were viewed as destabilizing in the context of the nuclear balance of terror. Strategic thought favoured deterrence, not defence. However, by the early 1980s, new technologies appeared which might make it possible to develop effective countermeasures. These included lasers, charged particle beam weapons, which are effectively a stream of tiny bullets—atoms or subatomic particles—and electromagnetic guns, which fire projectiles faster than is possible with chemical propellants. These systems would be mounted in ships, aircraft, orbiting space platforms, and on the ground. The best time and place to knock out missiles is in the boost phase soon after launch, when the engine is still burning, but it was theoretically possible to intercept them in space or on the way down.
The initiative was announced in 1983 and was immediately dubbed ‘Star Wars’, after the science fiction film. Preliminary feasibility studies indicated the system would be impossibly expensive and the expense would arguably be wasted if even a few nuclear missiles got through. The USSR reacted angrily—understandably, as it committed them to a new arms race which they could not afford. Amid national and international obloquy and mockery, progress could only be made very discreetly.
The end of the Cold War gave SDI a new lease of life. While it would probably have been impossible to build a shield against a determined nuclear strike by either superpower, the prospect of a rogue Russian general or a Middle Eastern potentate with a limited number of nuclear weapons launching one ‘out of the blue’ appeared real. The 1991 Gulf war showed that incoming ballistic missiles could be intercepted (though not as reliably as people were told at the time). Scud missiles fired at Israel and Saudi Arabia were engaged by Patriot missiles. It might be more feasible to provide ‘Global Protection Against Limited Strikes’ (GPALS) or ‘Theatre High Altitude Air Defence’ (THAAD), to protect an armed force deployed in a distant theatre against short-range attack by Scud-type missiles. The USA has successfully tested lasers mounted in Boeing aircraft designed to intercept missiles in flight. The UK launched a $5 million study into ballistic missile defence before the 1997 general election, and it was supposedly examined in the 1998 Strategic Defence Review, but the cost appears to have frightened the government. For the near future, deterrence will remain the preferred option, although the USA revived the idea, now called National Missile Defense (NMD) in 2000.
— Christopher Bellamy
