What Churchill called 'jaw-jaw' has produced nothing, except more provocations. In recent weeks, North Korea has detonated a nuclear bomb and violated U.N. Security Council prohibitions by launching ballistic missiles. It has threatened war against South Korea, repudiating the July 1953 armistice agreement and thus ostensibly reverting to a state of war with the United States. It has also sentenced two American journalists -- Euna Lee and Laura Ling -- to 12 years in a labor camp. These are extreme provocations. Only a military attack could exceed them. Our response, of course, must be diplomatic. But only a very special...