LONDON — President Trump on Wednesday called Prime Minister Justin Trudeau of Canada “two-faced,” after a video surfaced that showed him venting to other world leaders about Mr. Trump’s behavior at a NATO anniversary celebration designed specifically to avoid unwanted disruptions.
“Well, he’s two-faced,” the president said when asked about the video. After a long pause, he added, “He’s a nice guy. I find him to be a very nice guy.”
Mr. Trump, who was taking questions from reporters ahead of a meeting with Chancellor Angela Merkel of Germany, attributed Mr. Trudeau’s frustration to the American leader’s pressure campaign to increase Canada’s military spending to 2 percent of its economic output.
“He should be paying more than he’s paying,” Mr. Trump said. “I called him out on that, and I’m sure he wasn’t happy about it, but that’s the way it is.”
The brief video showed grinning world leaders at a Buckingham Palace reception on Tuesday night, apparently commiserating about the president.
“He was late because he takes a 40-minute press conference at the top,” Mr. Trudeau says to a small group that includes President Emmanuel Macron of France, Prime Minister Boris Johnson of Britain, Prime Minister Mark Rutte of the Netherlands and Princess Anne.
Mr. Trudeau does not mention Mr. Trump by name during the exchange, in which the Canadian leader appears to be discussing the day’s bilateral meetings.
“You just watch his team’s jaws drop to the floor,” Mr. Trudeau says at another point. Mr. Macron is also seen participating animatedly in the conversation, but his comments cannot be heard. Mr. Johnson is seen smiling.
None of the world leaders seem to realize that the conversation is being recorded. By the afternoon, some of the participants were seeking to distance themselves from the perceived criticism of Mr. Trump.
During a news conference, Mr. Johnson claimed that he had not been party to any discussion about Mr. Trump. “That’s complete nonsense, and I don’t know where that has come from,” he said. “I really don’t know what is being referred to there.”
The hot-mic incident was not the only moment that upended hopes for a drama-free NATO gathering.
On Tuesday, Mr. Macron put Mr. Trump on the defensive during a tense 45-minute appearance in which he aggressively challenged the American president’s vision for NATO and his handling of a military conflict involving Turkey. For Mr. Trump, it was a rare face-to-face meeting with another world leader in which he was not driving the conversation.
It was also not the first time that Mr. Trump and Mr. Trudeau have publicly clashed, or that Mr. Trump has accused Mr. Trudeau of misrepresenting himself.
Last year, Mr. Trump derided the Canadian leader as “very dishonest and weak” after Mr. Trudeau pledged at a Group of 7 summit in Quebec City that he would retaliate against United States tariffs on steel and aluminum products. Mr. Trump wrote on Twitter at the time that Mr. Trudeau had acted “so meek and mild” when they met face to face.
Mr. Trump has long bridled at the idea of other world leaders poking fun at the United States, and part of his 2016 presidential campaign pitch to voters was that his election would change how America was viewed abroad. “The world is laughing at us,” he said frequently during the campaign, criticizing the leadership of President Barack Obama.
In June 2017, when he announced that the United States would withdraw from the Paris climate agreement, Mr. Trump said: “We don’t want other leaders and other countries laughing at us anymore. And they won’t be. They won’t be.”
In 2018, laughter broke out at the United Nations General Assembly when Mr. Trump claimed that his administration had “accomplished more than almost any administration in the history of our country.”
The president insisted at the time that he was not the target, saying, “They weren’t laughing at me, they were laughing with me.”
None of the NATO leaders on Wednesday publicly acknowledged that they were talking about Mr. Trump in the uncomfortable video. But the clip loomed over the gathering of NATO leaders on Wednesday morning at The Grove, a country resort in Hertfordshire, where they met for a group photograph and welcome ceremony.
The leaders took the stage one at a time to greet Mr. Johnson and the NATO secretary general, Jens Stoltenberg, and pose briefly before the assembled news cameras.
Mr. Johnson greeted Mr. Trudeau with a handshake and a soft pat on the arm as they stood onstage together. Mr. Macron said hello to Mr. Johnson with a tap on the hand, and lingered, making jovial small talk before exiting the stage.
Mr. Trump arrived late to the meeting, just outside London, and shortly before he was due to emerge on the stage, an aide appeared to inform Mr. Johnson of a delay.
“We’re live now,” Mr. Johnson, who seemed perturbed, said to the aide before asking how long the delay would be. “A half an hour? 45 minutes?”
“How are we doing?” Johnson asked the aide few minutes later. “Come on!”
After the two co-hosts lingered onstage for about five minutes, rocking back and forth on their heels, Mr. Trump emerged and patted Mr. Johnson on the back.
Later in the morning, Mr. Trump politely shook hands and exchanged a few words with Mr. Trudeau before the general meeting of NATO leaders. Mr. Trump also wrote on Twitter that he had “enjoyed my meeting with the Prime Minister @BorisJohnson of the United Kingdom at @10DowningStreet last night,” noting that the two had discussed “numerous subjects including @NATO and Trade.”
In addition to Mr. Trump’s meeting with Ms. Merkel, he was scheduled to hold meetings with the prime minsters of Denmark and Italy, and to participate in a working lunch with representatives of Estonia, Greece, Latvia, Poland, Romania, Lithuania, Bulgaria and Britain.
Mr. Trump was also expected to hold a news conference before his departure, but on Wednesday he appeared to abruptly cancel those plans.
“We’ll go directly back,” he said. “I think we’ve done plenty of press conferences. Unless you’re demanding a press conference. But I think we’ve answered plenty of questions.”
The viral video clip was not only seen as a potential embarrassment for Mr. Trump. Mr. Trudeau also drew criticism for speaking so freely in a setting where his remarks could be recorded.
“By this point in his tenure, the prime minister should realise that events with pool cameras need to be approached and managed as on the record events,” Andrew MacDougall, who was a spokesman for Mr. Trudeau’s predecessor, Stephen Harper, wrote on Twitter.
“Hopefully this gaffe doesn’t wind the President up at a sensitive time” for United States-Canada relations, Mr. MacDougall wrote.
Chris Rands, a producer at the CBC’s Parliamentary news bureau in Ottawa, said he had first unearthed the video while searching for images of Mr. Trudeau in footage from Buckingham Palace.
Mr. Rands added that based on his listening, Mr. Trudeau was discussing Mr. Trump’s surprise announcement that a Group of 7 summit meeting next June would be held at Camp David rather than the Trump National Doral golf resort in Miami.
Megan Specia contributed reporting from London, and Ian Austen from Ottawa.