The far-right party Alternative fur Deutschland has enjoyed rising popularity as anti-immigration sentiment among Germans intensifies. If Germany’s political landscape shifts in a rightward direction, together with growing misgivings about the United States’ retrenchment from the world and its commitment to Europe’s security, it is not inconceivable that Germany’s neighbors will begin to fear Berlin’s power and intentions in a way they haven’t for decades.

There are already signs of a debate within Germany about the desirability of a nuclear deterrent in some form. While this does not mean that a European conflict driven by fear of Germany is inevitable as perhaps it was a century ago, American policymakers should not assume that the present post-World War II stability in Europe will last forever.

Those who diminish the enduring relevance of America’s security presence in Europe should remember that NATO sought to do more than keep Russia at bay. It has also been instrumental in keeping the continent’s largest states at peace with each other. That in turn has paid America significant dividends, which could be lost if the American people sanction Trump’s turn away from the transatlantic order.