It is frequently said that the decision to invade Iraq was the worst U.S. foreign policy decision since Vietnam. Actually, it was worse than Vietnam, and the worst in American history, for two reasons. One is that so far we probably have paid no more than 20 percent of the eventual costs of that decision, which enhanced Iran's ascendence. The other reason is that America gradually waded waist-deep into Vietnam without a crossing-the-Rubicon moment — a single, clear, dispositive decision. In contrast, the protracted preparation for invading Iraq was deliberative and methodical. It is not true that, as the current president and the virulent left insist, President George W. Bush and his senior advisers "lied" about Iraq's possessing weapons of mass destruction. They simply got things wrong, which conservatives, especially, understand was an event not without precedent in the annals of government.