While Vladimir Putin's actions in Crimea are worthy of international censure, a more imminent threat to world peace is impasse over Iran. There has been a sense in recent days that this was no ordinary week in the life of the planet. Our already bloodstained 21st-century history — unfolding once again in uncertain and threatening ways — seemed to be opening a new chapter. Two events last Tuesday in world capitals more than 2,000 kilometres apart best symbolized this. But which of these events do you think poses the greatest potential danger to world peace? In Moscow, a preening, self-satisfied...