Washington — Americans are starting to see the full, global implications of having a president who is ignorant of history, driven by impulse, immune to advice and dead to the romance of American ideals.

The betrayal of the Kurds has damaged President Donald Trump so badly — including among Republican legislators — because it so perfectly captures the essence of his approach to foreign affairs. There is the devaluing and abandonment of traditional friends (the Kurds are “not angels” and “didn’t help us with Normandy”). There is the surrender to strongmen (granting Turkey’s Recep Tayyip Erdogan a free hand in Syria, and ceding Russia’s Vladimir Putin a broader role in the Middle East). There is the absurdly contracted definition of American interests (events in Syria are unimportant because they are not on “our border”). There are the blustery threats to cover his humiliation (the U.S. will “swiftly destroy” Turkey’s economy with sanctions). And there is the inevitable and delusional pronouncement of success (the debacle was “strategically brilliant”).

This set of urges and instincts is leaving its mark on American influence. Trump’s bumbling retreat from alliances, from responsibility and from basic sanity has sown discord in Europe and created new playgrounds for Russian meddling. It has also left a vacuum of influence in the Pacific that is being filled by China. The damage to American interests is considerable and growing.

The cost of betraying a friend in battle — particularly to appease an authoritarian thug — is clear. It makes every friend and ally less likely to trust America. But what gets less attention is the cost of betraying American principles, particularly on human dignity. When Trump leaves the Kurds to ethnic cleansing, or is dismissive of the rights of protesters in Hong Kong, he is not only dishonoring national principles. He is forfeiting a decisive American advantage.

The world, no doubt, is complex and fallen, and often requires ambiguous choices. And there are limits to the influence of any single nation. But American ideology — a belief that the rights of life and liberty are universal endowments — is not an altruistic add-on to its “real” interests. It is an instrument by which those interests are realized.

It mattered greatly to the outcome of the Cold War that the aspirations of the average Czech or Polish citizen — for freedom, self-government and a life of simple dignity — were opposed by the Soviet Union and supported by the United States. In a very real way, American interests were achieved only when Czech and Polish aspirations were fully honored. Disregarding or discounting human rights would not only have violated the principles that led America into the world; it would have squandered a serious strategic advantage.

The same is true today concerning American competition with China in Africa. Chinese aims have little moral content. The Chinese government seeks resources and influence by cooperating with oppressive governments, buying off elites and encouraging African debt. As a matter of policy (and hopefully a matter of practice), America, in contrast, encourages health, human development, self-government and access to global markets. Chinese goals are often achieved at the expense of average Africans; American goals are achieved by their flourishing. We will see, in the long run, which approach is wiser.

Donald Trump’s conception of “America First” not only serves Chinese and Russian interests; it is an attempt to reshape American foreign policy on a Chinese or Russian model — devaluing democratic universalism in favor of raw nationalism.

This presents a practical problem. Since World War II, America has been a very different kind of hegemon. We committed American resources, and the lives of American military forces, to a rules-based international order in which other free countries could thrive, rather than a zero-sum struggle of great powers. Bluntly put: A Pacific dominated by Japan was a nightmare for the rest of Asia. A Pacific patrolled by American ships is good for the rest of Asia. The Warsaw Pact succeeded by intimidation and repression. NATO succeeded by partnership.

And because America exercised power without conquest, and sought wealth without exploitation, it helped forestall a concerted challenge to its preeminence. If “America First” means the reduction of American influence to the raw pursuit of its own power and wealth, it will invite question and challenge.

These are the real stakes of the debate on human rights. If the lives of Kurds and Chinese really mean nothing to America, then American ideology is a sham, and American influence is correspondingly less justified. Trump’s amoral foreign policy is a source of shame, and a source of danger.

— Michael Gerson is a columnist for Washington Post Writers Group.