One night in June 1984, a test ICBM soared up from Vandenberg Air Force Base in California. Thousands of miles away in the middle of the Pacific, another rocket was launched on Kwajalein Island. It contained an infrared sensor powerful enough to detect heat from a human body 1,000 miles away. Closing at 15,000 m.p.h., the rocket locked onto the ICBM, intercepting it in midflight and destroying it by sheer physical impact. So devastating was the hit that the remaining shards of the ICBM's warhead measured less than an inch across.
Pentagon officials were ecstatic about the results of the $300...