As it turns out, electing a president with literally no relevant experience is a lot like asking someone who didn’t attend dental school to perform a root canal. It’s painful, both parties look stupid for the idea, and, ultimately, the cure might be worse than the disease. And so it goes with human root canal Donald Trump, whose utter ignorance, combined with a profound disinterest in learning on the job, has frequently defined his interactions with foreign leaders—particularly allies that the U.S. has traditionally relied upon for economic, military, and political support.

In January, he left Australian Prime Minister Malcolm Turnbull flummoxed and frustrated when he berated his counterpart over an agreement Barack Obama had struck to take in a small number of refugees, failing at every turn to grasp basic facts about the policy. The deal is “going to kill me,” Trump insisted, even as Turnbull tried to explain that it was consistent with the White House travel ban. Trump called the agreement a “stupid deal” that would make him “look terrible,” said Vladimir Putin had been more pleasant, and then effectively hung up. The call went so badly that somebody with access to the transcript saw fit to leak the entire rambling mess to The Washington Post.

That same month, Trump failed to convince Mexican President Enrique Peña Nieto to stop saying publicly that he wouldn’t pay for a border wall, and threatened to invade Mexico in a conversation the White House described as “lighthearted.” In May, he used a speech at the new NATO headquarters to grouse about how much the building cost and to lecture allies about not paying their “bills.” During the same trip, he called Germans “very bad” for the “millions of cars they sell in the U.S.” Throughout his first 11-plus months in office, he’s shoved a world leader out of the way to be in the prime position for a photo op, engaged in a series of wildly uncomfortable handshakes and, miraculously, managed to anger Canada. Last month, he got into a Twitter spat with British Prime Minister Theresa May, who hit Trump with a rare public admonishment after he shared several hate videos from an anti-Muslim fascist group in the U.K. (“Don’t focus on me, focus on the destructive Radical Islamic Terrorism that is taking place within the United Kingdom,” he hit back. “We are doing just fine!”)

The tension between Trump’s supreme confidence and total ignorance tends to produce a vindictive streak that America’s allies have tried their best to avoid. French President Emmanuel Macron took his cues from Saudi Arabia and treated Trump to a military parade, which so cheered the U.S. president that he reportedly suggested he might not pull out of the Paris climate accord, after all. (He later withdrew anyway, confusing the French.) Japan’s Shinzo Abe mollifies him with golf. India lavishes praise on his daughter, Ivanka Trump. But not everyone has figured out how to successfully play the world’s most credulous, easily flattered leader. Germany’s Angela Merkel, who has a doctorate in quantum chemistry and is clearly leaps and bounds more intelligent than Donald “I’m, like, a really smart person” Trump, has struggled to make sense of the 45th president. She tried befriending Ivanka, of course. But no matter what she does, Merkel apparently can’t prevent Trump from coming away from their conversations looking like what he is: an idiot. The New York Times has new details about the ex-beauty-pageant owner’s first chat with the German chancellor, where it all went wrong: