Early in 2007, as the American presidential campaign started to gather momentum, critics of Pres. George W. Bush’s War on Terror invented a scheme that allowed them to oppose the administration’s strategy while dodging charges of appeasement. Under that scheme, Iraq was presented as “the bad war” or, according to Sen. Barack Obama, “the wrong war, at the wrong time, and in the wrong place.” In contrast, Afghanistan was presented as “the good war,” the “just war,” or even “the necessary war.”

The argument was that the war in Iraq was wrong because it had not been explicitly approved by the …