"He's two-faced," Trump said. "I find him to be a very nice guy but the truth is I called him out on the fact that he's not paying 2% (of GDP on Canada's defense budget) and I guess he's not very happy about it."
"He's not paying 2% and he should be paying 2%. It's Canada, they have money and they should be paying 2%. So I called him out on that and I'm sure he wasn't happy about it but that's the way it is."
The U.S. leader made the remark while taking questions from reporters alongside German Chancellor Angela Merkel at the 2019 NATO summit in London. Trump subsequently canceled a planned press conference moments later, announcing via Twitter that he would be "heading back to Washington" after Wednesday's meetings conclude.
A video surfaced on social media late Tuesday purporting to show Trudeau, French President Emmanuel Macron, U.K. Prime Minister Boris Johnson and Dutch Prime Minister Mark Rutte discussing Trump's press conference with NATO Secretary Jens Stoltenberg.
In the hot mic clip, which the people involved didn't realize was being taken, Johnson asks Macron: "Is that why you were late?" to which Trudeau steps in and says: "He was late because he takes a 40-minute press conference off the top."
It is not clear who exactly Trudeau was referring to in the footage, but it has been widely speculated that he was referring to Trump's remarks alongside Stoltenberg Tuesday. Trump's remarks with the NATO chief lasted 53 minutes, according to a White House transcript, when the itinerary had suggested that it would last 20 minutes.
Trudeau also appears to say that he saw U.S. officials' "jaws drop to the floor." However his words don't follow directly from his previous comments in the video.
According to Reuters, Trudeau said Wednesday that he had a "great meeting" with Trump and attributed some of his surprise to the president's "unscheduled announcement" that next year's G-7 summit would be held at Camp David in Maryland.
Representatives for both Johnson and Macron declined to comment on the recording. A spokesperson for Trudeau's office wasn't immediately available for comment when contacted by CNBC.
This year's NATO summit has been marred by disputes between allies of the 29-member organization. Macron has claimed the transatlantic group is suffering from a "brain death," while Turkish leader Recep Tayyip Erdogan said he would oppose NATO's plan for defense of Baltic countries if it does not recognize groups the country deems as terrorists.