Canadian Prime Minister Justin Trudeau "stabbed us in the back" with a "double cross" at the G7 summit, National Economic Council Director Larry Kudlow said Sunday, ratcheting up already sky-high tensions between the two neighboring allies.

"He holds a press conference, and he says the U.S. is insulting, and Canada has to stand up for itself," Kudlow, the White House's top economic adviser, said. "They have enormous tariffs, tariffs on certain dairy products. ... He was polarizing."

Kudlow, who referred to Trudeau's actions several times as a "betrayal," told CNN's Jake Tapper on "State of the Union" that Trudeau "really kind of stabbed us in the back."

"You know what, he did a great disservice to the whole G7," Kudlow added.

He called Trudeau's post-summit press conference, in which he said Canada will not be "pushed around" by the U.S. after Trump had already left the meeting, a “sophomoric, political stunt for domestic consumption.”

“President Trump played that process in good faith," Kudlow said. "So, I ask you: He gets up in the airplane and leaves, and then Trudeau starts blasting him at a domestic news conference? I am sorry, that’s a betrayal. That’s a double cross.”

But, Kudlow said, the animosity wouldn't derail the decades-old North American Free Trade Agreement, which Canada and the U.S. are currently renegotiating with Mexico.

"We won't withdraw from NAFTA," Kudlow said. "We're heavy into negotiations and the negotiation will either be bilateral or they'll be trilateral."

Trump was aboard Air Force One heading to Singapore for a historic summit with North Korea's Kim Jong Un when he issued a pair of tweets Saturday criticizing the G-7 host and stepping back from the generally positive tone that had ended the two-day meeting.

A few hours earlier, Trudeau had told reporters that all seven leaders had come together to sign the joint declaration.

TOP WH ECONOMIC ADVISER: CANADA 'OVERREACTING' TO STEEL AND ALUMINUM TARIFFS

Trudeau said he had reiterated to Trump that tariffs would harm industries and workers on both sides of the U.S.-Canada border. He said unleashing retaliatory measures "is not something I relish doing" but that he wouldn't hesitate to do so because "I will always protect Canadian workers and Canadian interests."

"As Canadians, we are polite, we're reasonable, but also we will not be pushed around," Trudeau said, and he described all seven leaders coming together to sign a joint declaration despite having "some strong, firm conversations on trade, and specifically on American tariffs."

In the air by then, Trump tweeted: "Based on Justin's false statements at his news conference, and the fact that Canada is charging massive Tariffs to our U.S. farmers, workers and companies, I have instructed our U.S. Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the U.S. Market!"

He followed up by tweeting: "PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that, "US Tariffs were kind of insulting" and he "will not be pushed around." Very dishonest & weak. Our Tariffs are in response to his of 270% on dairy!"

A spokesman for Trudeau did not address Trump's insults in a statement. "We are focused on everything we accomplished here at the #G7 summit," spokesman Cameron Ahmad said. "The prime minister said nothing he hasn't said before — both in public, and in private conversations with the president."

The Associated Press contributed to this report.