The White House seems to assume that, whatever the lofty aspirations of Berlin, Obama’s governing approach is what Americans want and the country can afford. While acknowledging “very real and legitimate” humanitarian interests in Syria — some 80,000 people have been killed, and millions have lost their homes — Obama recently said his “bottom line” has to be “what’s in the best interest of America’s security.” Judging by conversations with his team, there’s also an assumption that such assessments were clear during the Cold War but are hopelessly more complex now.

But those judgments have never been easy. During the Cold War, too, Americans fought bitterly over the size of the defense budget, the wisdom of interventions and the morality of supporting unsavory but friendly dictators. Over the decades the country made terrible mistakes overseas. But U.S. engagement and influence also helped to gradually open the world to more democracy and more prosperity.

To reduce such engagement — to concentrate on “nation-building at home,” as Obama has put it — may seem the practical, hard-headed choice. But eventually the country always re-learns the lesson that as states such as Syria or Libya spin out of control, the danger is hard to contain.