Trump’s behavior in private meetings with several European leaders has caused not only offense but also fundamental confusion over whether the president of the United States remains committed to NATO, the liberal world order and the survival of the European Union, Biden said.

One European diplomat told me that in a private White House meeting in March, Swedish Prime Minister Stefan Lofven explained to Trump that Sweden, although not a member of NATO, partners with the alliance on a case-by-case basis. Trump responded that the United States should consider that approach. A senior administration official told me Trump was joking.

At the failed Group of Seven summit in Quebec this month, according to the Eurasia Group’s Ian Bremmer, Trump disrespected Merkel to her face, throwing two Starburst candies on a desk and saying, “Here, Angela, don’t say I never gave you anything.”