It was a plan that read like science fiction: A system armed with an array of space-based X-ray lasers would detect and deflect any nukes headed toward the United States.
President Ronald Reagan saw the proposed Strategic Defense Initiative (SDI) as a safeguard against the most terrifying Cold Waroutcome—nuclear annihilation. When Reagan first announced SDI on March 23, 1983, he called upon the U.S. scientists who “gave us nuclear weapons to turn their great talents to the cause of mankind and world peace: to give us the means of rendering these nuclear weapons impotent and obsolete.”
From the start, politicians and scientists argued that SDI was overambitious. The technical hurdles required to achieve SDI (which included a number of proposed designs and weapons—not just space-based lasers) seemed so incredible at the time that Massachusetts Senator Edward Kennedy referred to it as ''reckless 'Star Wars' schemes.'' The ‘Star Wars’ moniker stuck. Over the course of 10 years, the government spent up to $30 billion on developing the concept, but the futuristic program remained just that—futuristic. It was formally scrapped by President Bill Clinton in 1993.
Despite criticisms from politicians, many scientists and others that the SDI was impractical, expensive and dangerous, the concept was developed during a frightening era.