Ronald’s out. Donald’s in.

President Trump’s trip to Europe is being portrayed by both him and his critics as revolutionary. He tells us that he single-handedly and miraculously got members of NATO to increase their defense spending sharply. His critics claim that he single-handedly wrecked the Western alliance by sowing doubt and discord among America’s closest partners.

Neither assertion is really true. Trump’s demands are, in fact, familiar American demands. President Barack Obama routinely asked the same of NATO allies. His first defense secretary, Robert M. Gates, chose to deliver his “farewell” speech in Europe — weeks before leaving office — on precisely this subject. He predicted a “dwindling appetite . . . in the American body politic . . . to expend increasingly precious funds on behalf of nations that are apparently unwilling . . . to be serious and capable partners in their own defense.” And he warned that “future U.S. political leaders, those for whom the Cold War was not the formative experience that it was for me, may not consider the return on America’s investment in NATO worth the cost.”

Trump’s loud charge against Germany this week — that it has become too dependent on Russian natural gas — does have considerable merit. The Germans have eagerly signed up for an energy relationship with Russia that is strategically dangerous. Trump gets some of the dynamics wrong. It is not so much that by importing large amounts of natural gas from Russia, Berlin can be blackmailed. The Russians are equally dependent on German cash. But the new pipelines being built could allow Russia to threaten Eastern European countries by withholding energy supplies or jacking up prices, and Moscow has used and abused this energy card in the past.

Again, however, Trump’s complaint was often voiced by the Obama administration. And in neither of these cases is there any indication that Trump’s crude and aggressive approach has produced any results. If anything, it has made some Europeans feel that they have to push back. German Foreign Minister Heiko Maas reminded Trump that Germany is a vassal neither of Russia nor of the United States.

The real revolution, however, is in what Trump is doing with his foreign policy at home. He is continuing with his project, by intent or instinct, to remake the Republican Party. His approach abroad appears to be designed to create a new Republican foreign policy that is much closer to the party’s historical roots — distrustful of foreigners, alliances and treaties — and, in many senses, flatly isolationist. In his rallies, Trump describes America’s closest allies as “our worst enemies” and says they “kill us” on both security and trade. “We’re the schmucks,” he bemoans about America in its dealings with NATO and the European Union.

Jonathan Chait writes in New York magazine that “Trump is training his base to hate NATO and like Putin.” Indeed, Trump has been remarkably successful: Fifty-one percent of Republicans now believe the United States shouldn’t defend NATO allies unless they increase defense spending. Even more astonishingly, Trump seems to have reversed Republican attitudes toward Russia and its dictator, Vladimir Putin. At a recent rally, Trump said, “You know what? Putin’s fine. He’s fine. We’re all fine. We’re people.” Republicans are now twice as likely as Democrats to express a favorable opinion of Putin, and 56 percent of Republicans want to cooperate and engage more with Russia.

The Republican Party has proved remarkably malleable ideologically. The party of law and order now has deep distrust of the FBI. The party of free trade is now far more solidly behind protectionism than the Democrats. The party that celebrated President Ronald Reagan’s optimism about immigrants now contains a majority that supports separating families at the border and criminally prosecuting undocumented immigrants.

Trump’s political genius continues to be that he recognizes that the base of the party is ripe for this ideological revolution — that while the old Reaganite formula may still be subscribed to by Republican elites in Washington and New York, it’s not embraced out there in the grass roots.

Five years ago, one establishment Republican wrote that “the specter of isolationism is stalking the Republican Party. . . . It is hardly certain that isolationist sentiment will prevail. But it is critical . . . that national-security Republicans can answer the questions being raised, restore a coherent party platform and thereby thwart the new isolationism.”

Those words were written by John Bolton, now Trump’s national security adviser. It seems even the most stalwart national-security Republicans have accommodated themselves to the Trump revolution.