White House economic adviser Larry Kudlow accused Canada on Sunday of making "polarizing"
statements about the United States' trade policy, and said Trump had to pull out of a joint statement because his Canadian counterpart had "stabbed us in the back."
Trudeau "held a press conference and he said the U.S. is insulting. He said that Canada has to stand up for itself. He says that we are the problem with tariffs. The non-factual part of this is - they have enormous tariffs," Kudlow said on CNN's "State of the Union."
"Here's the thing," he added. "He really kind of stabbed us in the back," Kudlow added.
While Trump and Trudeau have had several seemingly congenial meetings and phone calls since Trump took office, they could not be more different in terms of policy. Trudeau is a progressive liberal, outspoken on feminism and the merits of diversity and who was close to former president Barack Obama.
Earlier in the day, Trudeau had sniped about Trump's late appearance at a women's empowerment breakfast, referring to "stragglers."
Trump's about-face sparked dismay and anger among Canadian and American free trade advocates alike.
"To our allies: bipartisan majorities of Americans remain pro-free trade, pro-globalization & supportive of alliances based on 70 years of shared values. Americans stand with you, even if our president doesn't," U.S. Republican Senator John McCain tweeted after Trump on Saturday.
Trudeau's former foreign policy advisor, Roland Paris lashed out at the U.S. president.
"Big tough guy once he's back on his airplane. Can't do it in person, and knows it, which makes him feel weak. So he projects these feelings onto Trudeau and then lashes out at him," Paris tweeted.
Trade experts who have watched Trump negotiate with tough words on Twitter before said the bark of Trump's tweets often exceeds the bite of his policy — but that this time, Canada might struggle to respond.
"The rhetoric has far outpaced the implementation," said Geoffrey Gertz, trade analyst with Brookings think tank in Washington. "Now we might be at a turning point ... (Canadians are) a little bit at a loss right now to figure out what to do."
But while Trudeau's months-long effort to reach out to U.S. politicians and business leaders at every jurisdiction and level may not have won over Trump, it may pay dividends if Trump's attack finally spurs support from business groups or Congress.
Republicans worry the dispute with Canada could become an issue in trade-dependent farm states ahead of November congressional elections.
"There's some movement within Congress now to rein in Trump on trade policy," Gertz said.
During the summit, Trump had changed the photo on his Twitter page to the "family photo" taken with other G-7 leaders.
Somewhere over the Atlantic, minutes after attacking Trudeau, he swapped that for a photo with soldiers saluting during the national anthem.