Donald Trump at the commemoration for Armistice Day in Paris on November 11, 2018Carlos Barria / Reuters

Returning from the World War I armistice commemoration in Paris, President Donald Trump reemphasized his view of America’s European allies. “We pay for large portions of other countries’ military protection,” he wrote on Twitter, and “it is time that these very rich countries either pay the United States for its great military protection, or protect themselves.” Trump’s criticisms are, of course, nothing new—since the 2016 campaign he has routinely highlighted the ways in which free-riding allies purportedly take advantage of American largesse.

But underlying the president’s position lies an assumption that is now worthy of close consideration: that the United States defends Europe, and stations troops on the continent, based on an impulse that is either fundamentally charitable, anachronistic, or both. As a result, it follows that we’ve been played by allies enriching themselves under our protection. Trump seems to believe that such altruism merits gratitude; the French, he observed, were “starting to learn German in Paris before the U.S. came along.”

The truth, however, is that the U.S. helps Europe because, in so doing, it helps itself. Twice in the first half of the 20th century, the United States went to Europe to end wars that had engulfed the world. These were not acts of charity, but of national self-interest. Following the Second World War, American leaders resolved not to permit such catastrophes to reoccur. Their solution was to remain in Europe, commit to its defense, and deploy troops there as a way to keep the peace. The bargain has been straightforward: America gets bases and a guarantee that we won’t have to fight alone; European allies get protection from the world’s foremost military. All get stability and peace on the continent.

The hardheaded interests at stake in European peace informed the moves even of the great presidential idealist Woodrow Wilson. He famously called for the world to “be made safe for democracy,” not only in light of democracy’s inherent value, but because “such a concert of free peoples” would “bring peace and safety to all nations,” including our own. “No peace can last,” Wilson said, “or ought to last, which does not recognize and accept the principle that governments derive all their just powers from the consent of the governed.”

Peace-seeking Americans, wishing to be free of German submarine warfare, seeking to enjoy the benefits of free travel and open commerce, had to fight for democracy.

Some 40 million casualties later, including 116,000 Americans killed, the United States lost its patience. It was done defending European friends, unwilling to serve as the peacekeeper of last resort. America withdrew from the continent, demobilized its forces, and isolated itself. That seemed the safest course for America; in retrospect at least, it obviously was not.

By 1940—a year before Pearl Harbor and Hitler’s declaration of war against the United States—Franklin D. Roosevelt was sounding the alarm about a possible British defeat in Europe and its implications for Americans. Should the British fall, he said, “the Axis powers will control the continents of Europe, Asia, Africa, Australasia, and the high seas—and they will be in a position to bring enormous military and naval resources against this hemisphere … All of us in the Americas would be living at the point of a gun—a gun loaded with explosive bullets, economic as well as military.”

Another world war fought and won, American leaders resolved not to replay the catastrophic half century of European history. There would be no withdrawal this time, and no demobilization, especially in light of Moscow’s drive for domination. Nor would the United States go it alone.

Washington led the establishment of NATO to keep, in the words of Lord Ismay, “the Soviet Union out, the Americans in, and the Germans down.” And so it has. Moscow never went to war in NATO territory; Europe emerged as America’s chief trading, diplomatic, and military partner; Germany evolved into a benign power unrecognizable to Bismarck or the Kaiser or the Third Reich. And America stayed.

Such are the reasons why the United States has defended Europe for seven decades, and fundamentally why it should continue to do so today.

Yes, it can be maddening when our European allies let their militaries atrophy and devote insufficient sums to defense spending. The United States has global interests and global security commitments; it defines not just Europe but the Middle East and Asia as strategically important. A militarily successful and politically sustainable NATO alliance depends on European allies bearing a fair share of the burden. In response to Trump’s criticisms, our allies have in fact moved their defense budgets in the right direction.

Yet low spending levels also represent a remarkable commentary on how unthinkable major war in Europe has become, after two millennia of nearly uninterrupted military competition and conflict. The problem surely would have been a surprise to the leaders who ended the Great War a century ago. Indeed, what the president sees as failure can also be construed as a kind of success: Worrying about European pacifism rather than European militarism is a luxury we are lucky to indulge. War is unthinkable in Europe? Let’s keep it that way.

Times change. Perhaps, some argue, the continued American presence in Europe is unnecessary in light of diminished threats, or it is desirable but too expensive, or maybe the continent is best left to fend for itself. It could even be the case that war on the continent wouldn’t overly damage fundamental U.S. interests, given our diversified economy, powerful military, protective oceans, and friendly neighbors.

And yet such notions have been popular before, with catastrophic consequences. Better to maintain an insurance policy among allies against threats that may or may not ever materialize. Better to build on historic success than inject greater geopolitical uncertainty at an unusually unsettled time in international politics. Better to do these things than not, because the defense of Europe serves the interests of the American people.

Trump traveled to Paris to honor those who understood this, who saw in their fight the enlightened self-interest that has served America so well for so long. We abandon Europe at its peril, and our own.

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