If a U-2 overflight could once provoke crisis, as the Francis Gary Powers incident did in 1960, the elaborately precise spy satellite systems of the U.S. and Soviet Union a decade later have created and enforced a de facto "open skies" policy between the two superpowers. Today such satellites slide through space like disembodied eyes recording an astonishing variety of information. Just over a month ago, for example, the Pentagon revealed that the latest Soviet S59 ICBM ground tubes are exactly 20 ft. in diameter.
Neither country, naturally, is very talkative about its...