Trump is not the first president to get frustrated over European defense spending. The U.S. spends about 3.6 percent of its gross domestic product on defense. Of the alliance’s 26 members, four others spend 2 percent of GDP or more on defense, a target reiterated most recently in September 2014. (For how the random the 2-percent figure is, read this.)

It’s not clear the U.S. has a well-defined view on which allies need to spend more, however. While Trump’s letter to Merkel urged Germany, which spends about 1.2 percent on defense, to spend more, U.S. Defense Secretary James Mattis said Germany’s spending plan was “right on track.” Mattis had harsher words for the U.K., which spends 2.1 percent of its GDP on defense, writing in a letter to his U.K. counterpart, Gavin Williamson, that unless the U.K. spends more on defense, it risks losing its place as the U.S. “partner of choice.”

Trump’s irritation at shouldering the financial burden of protecting the world is not unique to him. (Obama famously declared to The Atlantic’s Jeffrey Goldberg regarding U.S. allies that “free riders aggravate me.”) But what’s unusual about Trump is that he appears as quick to reject his allies’ assurances as he is to accept those of his adversaries. In the same week that The New York Times quoted Trump’s letter scolding Merkel, he also told Fox’s Maria Bartiromo of Kim: “I made a deal with him. I shook hands with him. I really believe he means it.”

Trump’s reading of ambiguous language in two very different contexts says more about how he views the world than it does about the underlying issues at stake. He has long said that U.S. partners, whether in trade or in military alliances, are taking advantage of it on a range of issues. The ambiguity of the 2014 Wales Summit Declaration that laid out the 2-percent target is irrelevant to this idea. Similarly, he believes his “great chemistry” with Kim will resolve a problem that his predecessors could not. The ambiguity in his joint declaration with Kim is irrelevant to this belief. This pattern of thinking, if restricted to defense spending, could have been a minor irritant in relations with U.S. allies, but taken with recent disputes over trade, climate change, and tariffs it signals a major fracture—if not an outright break—in the trans-Atlantic relationship.

This is especially the case since there’s another adversary Trump seems intent on believing: Russia’s Vladimir Putin. Faced with accusations from both European governments and his own intelligence community that the Russians interfered in U.S. elections on his behalf, Trump has repeatedly said that Putin assured him no such meddling occurred. And his seeming inclination to trust Putin’s intentions could further erode U.S. relations with NATO. Trump is set to meet Putin after a NATO meeting in mid-July, and he appeared to suggest that the U.S. was open to recognizing Russia’s annexation of Ukraine’s Crimea. The Russian takeover of a chunk of a European country understandably alarms leaders on the rest of the continent. It was that invasion, coupled with Russia’s support for breakaway parts of Ukraine, that resulted in tough U.S. and European sanctions on Russia—restrictions that specifically hurt European companies that have vast business dealings in Russia.