Don’t be fooled. The Greenland controversy might make for some better-than-average late-night TV, but it’s certainly no harmless sideshow. Rather, it’s the latest example of a particularly destructive element of the Trump presidency: the way the president’s myopic domestic struggles against the media and his critics bleed over into and do damage to U.S. foreign policy…

In less than a week, Trump had managed single-handedly to open a serious rift between America and a European ally—all because of one leaked report to the Wall Street Journal. The president didn’t decide that this week was the strategic time to broach the subject of purchasing Greenland with Denmark, and he didn’t decide to just ignore the leak and go about the normal business of being president. The leak caused a domestic controversy, so Trump felt compelled to wade in—regardless of what damage it might to do our relations with an ally…

But this incident is undeniably part of a far more worrisome trend. What it shows us once again is that President Trump sees his squabbles with his domestic political adversaries as the central struggle of his presidency. And he has no qualms about using U.S. foreign policy as a bludgeon in his fight against those adversaries, even if it means compromising America’s aims on the world stage.