There are two kinds of wars, we are told — wars of choice and wars of necessity. The former is to be avoided and the latter fought with appropriate reluctance. World War II was a good and necessary war but Vietnam was not. The war in Iraq was a matter of choice (also of imbecility) but Afghanistan was not — although it now may be. Wars can change over time. The one in Syria certainly has. It has gone from a war of choice to a war of necessity that President Obama did not choose to fight. A mountain of dead testifies to his mistake.

More than 60,000 people have been killed, most of them civilians. An estimated 650,000 refugees have fled across Syria’s various borders. They live in miserable conditions, soaked and frozen by the chilling rains of the Mediterranean winter, caked in mud. Children have died. More children will die.