U.S. President Donald Trump’s latest disastrous trip to Europe is over, but his feud with French President Emmanuel Macron over the latter’s suggestion of a European army is not. Far from simply being a tiff between two strong-willed leaders, the dispute demonstrates in microcosm just how dark and precarious the current moment in global politics is.

Trump’s behavior on the international stage is so boorish that it often brings to mind Winston Churchill’s quip about an earlier American statesman being “the only bull I know who carries his own china shop around with him.” Yet it was Macron who precipitated the current spat with comments before Trump’s visit to Paris as he marked the 100th anniversary of the end of World War I.

Contrary to what was widely reported, Macron did not quite say that the European Union needed a stronger military to protect itself from America. (He said that the EU faced cyberthreats that originated in a variety of locations, including Russia, China and the United States.) But he did claim that Europe was the “principal victim” of the U.S. decision to withdraw from the Intermediate-Range Nuclear Forces Treaty with Russia, presumably because Moscow’s response may be to increase the number of missiles putting European targets at risk.

He also revived calls for greater European strategic autonomy vis-a-vis an increasingly unreliable U.S., and he used his speech commemorating the armistice to obliquely argue that Trump’s sort of nationalism represents a grave threat to peace and stability.

Trump, of course, gave as good as he got, by calling Macron’s comments “very insulting” and then sulking his way through the armistice ceremony (at least until Russian President Vladimir Putin showed up). After returning to Washington, Trump followed up with a series of tweets ridiculing the notion of European security without America. Most noteworthy, he reminded Macron that France and Germany — the notional core of any enhanced EU defense capability — were mortal enemies prior to 1945. “They were starting to learn German in Paris before the U.S. came along,” he wrote. “Pay for NATO or not!”

Leave aside for a moment that the EU will not have any credible autonomous military capability for many years. Leave aside also that Macron’s comments about Trump and the U.S. were partially intended for domestic consumption. Finally, leave aside the profound oddity that it was Trump — who has displayed no attachment whatsoever to the trans-Atlantic relationship — giving a European leader a history lesson on the critical role America has played in pacifying the continent since World War II. The Trump-Macron dispute nonetheless shows two big things about the unsettled state of the world today.

First, Macron’s comments brought into the open the degree to which the Trump era is forcing foreign leaders, including longtime allies, to think harder about how they might adapt in a world where the U.S. is acting in indifferent, unhelpful or even unfriendly ways. So many aspects of Trump’s behavior — his skepticism of U.S. alliances and security guarantees, his avowed hostility toward the EU, his penchant for waging trade wars against friends as well as rivals, his deeply erratic and unpredictable nature — have profoundly shaken countries that have traditionally relied on Washington.

As Macron indicated, Trump’s unilateralism and glorification of nationalism are discomfiting to a continent where unrestrained nationalism led to devastating global wars twice in the 20th century.

Most U.S. allies and partners have so far chosen to keep their heads down, because they still value security and diplomatic cooperation with America, and because — in the near term, at least — they lack other options. This is why, back in August, German Chancellor Angela Merkel firmly rejected her foreign minister’s suggestion that the EU become a “counterweight” to an aggressive America. But make no mistake: Trump’s policies and rhetoric are forcing countries in Europe, East Asia and elsewhere to consider whether they need a geopolitical Plan B. The longer the current period in U.S. foreign policy continues, the stronger these inclinations will become.

Second, Trump’s response — particularly his comments that the pre-1945 tradition in Europe was not continental cooperation but blood-soaked competition — is telling in its own right. The “you’d be speaking German if it weren’t for us” taunt may be juvenile, and it probably strikes many observers as ridiculous. After all, what are the odds of another war between France and Germany today or anytime in the next five years?

Yet that reflex reveals how thoroughly our understanding of what is possible and what is absurd has been conditioned by a tradition of engaged U.S. statecraft that is now being challenged.

Until 1945, no one ever thought that the prospect of a Franco-German war was silly. It is only because the U.S. suppressed the forces of nationalism and rivalry in Europe — because it provided the security blanket underneath which Germany and France could become diplomatic partners — that the scenario now seems so outlandish.

If that American presence goes away, if the U.S. pursues a policy focused on dividing Europe rather than uniting it, why wouldn’t the continent return to the worst traditions of its past? Why wouldn’t the tensions between a powerful Germany and the nations on its flanks re-emerge? Given that nationalism — sometimes of a toxic and xenophobic nature — is already on the rise throughout the continent, who is to say that things couldn’t get much worse absent the steadying hand of the superpower across the Atlantic?

We have not reached this point yet, of course. But some scenarios that seemed thoroughly improbable even five years ago — British withdrawal from the EU, the election of an illiberal populist with authoritarian leanings as president of the U.S. — have already materialized. The Trump-Macron dispute is simply one more reminder that we need to rethink what is really unthinkable after all.

Bloomberg columnist Hal Brands is the Henry Kissinger distinguished professor at Johns Hopkins University’s School of Advanced International Studies.

In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.