Less gently put, Trump would be a president who could not reliably tell America’s enemies from its friends. He contemplates actions such as weakening U.S. security assurances to South Korea that might invite war. (Recall the outcome in 1950 of Secretary of State Dean Acheson’s implication that South Korea was outside America’s “defensive perimeter.”) Trump promises actions — like forcing the Mexican government to fund the great wall of Trump — that are, in the formal language of international relations, loony, unhinged, bonkers. His move to impose massive tariffs against China would earn derisive laughter at the World Trade Organization; if he persisted anyway, it might blow up the global trading order and dramatically increase tensions in Asia.

A Jacksonian role for the United States is positively dangerous in a world where many threats — terrorism, pandemic disease, refugee flows, drug cartels — emerge in failed states and hopeless places. It has never been more evident that the success of America depends on an expanding system of free trade, free markets, democratic governance and strong alliances — upheld, in Asia, Europe and elsewhere, by American security guarantees.

Trump’s version of American nationalism without reference to American principles is Putinism by another name. And it is just one more way that Trump would sully the spirit of the nation he seeks to lead.