We have marked the 80th anniversary of President Harry Truman’s fateful decision to drop atomic bombs on the cities of Hiroshima and Nagasaki (respectively, Aug. 6 and Aug. 9, 1945). To date, those two bombings represent the only instances in which nuclear weapons have been deployed in war. At least 150,000 Japanese perished -- a majority of them civilians. But the bombings were successful in...