ABSTRACT
Addressing the nation on 23 March 1983, President Ronald Reagan launched the Strategic Defence Initiative (SDI), a defensive system which would make nuclear weapons 'impotent and obsolete'. The system would form a space-based defensive shield – a kind of an invisible astrodome – using the high technology of futuristic space and ground-based laser weapons, and particle beams. The origin of ballistic missile development could be traced back to Adolf Hitler's Germany and the September 1944 launch of the V-2 ballistic missile against London. Anti-ballistic missile (ABM) work benefited from German scientists who perfected the Wasserfall surface-to-air missiles in Germany during the Second World War. In the Lyndon B. Johnson administration, the US was proceeding with its own ABM system, known as the 'Sentinel', as protection against a possible Chinese intercontinental ballistic missile (ICBM) attack. President Richard Nixon transformed Sentinel to the 'Safeguard' system. The SDI was motivated by political as well as strategic factors.
