There was something oddly disproportionate about the just-concluded nuclear summit to which President Obama summoned 46 world leaders, the largest such gathering on American soil since 1945. That meeting was about the founding of the United Nations, which 65 years ago seemed an event of world-historical importance. But this one? What was this great convocation about? To prevent the spread of nuclear material into the hands of terrorists. A worthy goal, no doubt. Unfortunately, the two greatest such threats were not even on the agenda.