RUTHFULLY YOURS

But it’s not only Mr. Trump and his supporters whose attitudes should worry Europe. Some of Europe’s closest friends are also increasingly discouraged.

The American intellectual class once rang with inspired and sometimes envious praise of a rising Europe. In 2002 an influential Atlantic essay argued that the “rising challenger” to American primacy was “not China or the Islamic world but the European Union, an emerging polity that is in the process of marshaling the impressive resources and historical ambitions of Europe’s separate nation-states.” It warned Americans to prepare for the emergence of a new superpower on the world stage.

This is not what Europe’s friends see today. Philanthropist George Soros—one of Europe’s keenest observers and strongest defenders—predicted last week that unless things change, “the European Union will go the way of the Soviet Union in 1991.” He is far from alone among the EU’s supporters in bewailing the bloc’s inability to master its growing difficulties.

Decline, not the Donald, is the specter haunting Europe today. The numbers make this clear. Some readers objected to World Bank data in last week’s column showing that, in dollar terms, the eurozone economy had not recovered from the 2008-09 financial crisis. In euro terms, they point out, eurozone gross domestic product has been growing. But even using the euro-denominated figures issued by the European Central Bank, the growth rate from 2009 to 2017 was only 0.6% per year. That’s anything but robust.

Mr. Trump’s tweets aren’t the reason populists are governing Italy and the gilets jaunes revolt has shaken Emmanuel Macron’s reform efforts in France. Since the financial crisis, the Italian economy—measured in euros—has been shrinking at an average rate of 0.5% a year, while the French economy has been growing at an average of only 0.8%. Only the gush of cheap energy made possible by American fracking keeps these fragile economies afloat; at an oil price of $125 a barrel, the eurozone—and its banking system—might well face another economic crisis.

Asked about the importance of European unity to the U.S. in January 2017, President-elect Trump told the Times of London: “I never thought it mattered. Look, the EU was formed, partially, to beat the United States in trade, OK? So I don’t really care if it’s separate or together, to me it doesn’t matter.”

But whatever Mr. Trump thinks, European unity matters to U.S. interests. A strong Europe and only a strong Europe can stabilize the region, manage migration and refugee issues in a humane and sustainable way, contain Russia at a reduced cost, and provide the markets that American companies need for growth. On its current course the EU cannot achieve these goals, and the decay or dissolution of the union would only make things worse.

It does not advance U.S. interests for Europe to go the way of the Soviet Union or stay deadlocked in decline. A vibrant Europe whose unity is based on common-sense cooperation and pro-growth economic policies suits America best, but neither the immobilism of Angela Merkel’s Germany nor hostile rhetoric from the White House can bring that about.

Instead of reforming itself, a beleaguered European establishment is circling the wagons against critics at home and abroad. Meanwhile, an American president who would rather have a Diet Coke with Viktor Orban than with Angela Merkel is hurling rhetorical firebombs across the Atlantic. No good will come of this sterile trans-Atlantic feuding, though both Russia and China will be happy to exploit the tensions and cleavages that result.

Europe continues to drift toward irrelevance on the global stage. Josef Joffe, longtime editor and publisher of Die Zeit and one of Europe’s most seasoned and respected diplomatic observers, argues in the February issue of Commentary that the Soros warning may be too late. The grand project of building the EU into a superpower has already imploded: At the level of world politics, “ ‘Europe’ does not exist.”

That lifelong proponents of European values like Messrs. Soros and Joffe increasingly share Mr. Trump’s harsh view of the EU as an irrelevant failure should make even the most headstrong Brussels partisans reflect. Europe is not on a sustainable path; nobody knows this better than those who love and value it most.