Human beings often choose self-delusion over painful reality, and so in the days and weeks to come, we will hear reassurances that the NATO alliance is in good shape. After all, there have been spats in the past — over the Suez crisis in 1956, Vietnam in the 1960s and ’70s, missile deployment in the Reagan years and, of course, Iraq. American presidents have been complaining about shortfalls in European defense spending for decades. President Trump is not wrong to criticize Germany’s pipeline deal with Russia. As for this week’s fractious summit, we are urged to focus on the substance, not the rhetoric. U.S. forces in Europe have been beefed up in recent years, and new plans are in place to resist Russian aggression. On the ground, the alliance still functions.

All true, but unfortunately beside the point. Small troop deployments and incremental defense increases don’t mean much when the foundations of the alliance are crumbling — as they are and have been for some time. And pointing to previous differences ignores how much political and international circumstances have changed over the past decade. Europe faces new problems, as well as the return of some of the old problems that led to catastrophe in the past; and Americans have a very different attitude toward the world than they did during the Cold War. This is not just another family quarrel.

The transatlantic community was in trouble even before Trump took office. The peaceful, democratic Europe we had come to take for granted in recent decades has been rocked to the core by populist nationalist movements responding to the massive flow of refugees from the Middle East and Africa.