War arrives unexpectedly. Sometimes a simmering crisis erupts, at other times an unscrupulous leader seeks gain by surprise attack, at other times events simply drift out of control. The biggest problem for those who initiate war is to figure out its scope and when and how it will end, simply because there are too many variables at play. As the saying goes, no war plan survives contact with the enemy. If war between two nuclear-armed states is itself self-destructive, limited war is a chimera best avoided.