LONDON – Imagine for a moment that the U.S. gave up all its nuclear weapons, a totally farfetched idea but one supported by such luminaries as former secretary for defense, Robert McNamara, the late Paul Nitze, Ronald Reagan’s hard-line negotiator on nuclear arms and General George Lee Butler, the former chief of U.S. strategic (i.e. nuclear) forces. As his successor, General Eugene Habiger, has said, “We have reached the point where the senior military generals responsible for nuclear forces are advocating more vocally, more vehemently, than our politicians, to get down to lower and lower weapons”. But imagine if it did happen what effect this would have on Russia. It would then move immediately to close down its decaying early warning system and its hair-trigger nuclear posture, which former senator Sam Nunn sees as a likely cause of accidental nuclear war. Imagine what effect it would have on Iran, Syria,...