President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE’s top economic advisers mounted scathing attacks against Canadian Prime Minister Justin Trudeau during appearances on the Sunday talk show circuit, arguing he had undermined Trump's standing ahead of his talks with North Korean leader Kim Jong Un.

White House economic adviser Larry Kudlow said Trudeau's comments at a press conference after the Group of Seven (G-7) summit amounted to a "betrayal," while Peter Navarro, a Trump trade official, declared there was a "special place in hell" for foreign leaders who double-cross Trump.

The stunning remarks widened a rift on trade policy between the United States and Canada, which has joined the European Union and Mexico in blasting Trump's decision to impose tariffs on imports of steel and aluminum.

The latest condemnation of Trudeau followed Trump's decision to not sign a G-7 communique after a weekend meeting of seven major industrialized economies, a group of traditional U.S. allies.

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Kudlow lashed out at Trudeau first during an appearance on CNN's "State of the Union."

He argued Trudeau's press conference criticisms of Trump's trade tariffs were inappropriate because of Trump's upcoming meeting with Kim, and because they represented a shift from the more cooperative work that had been done to form the communique from the seven nations.

"You just don't behave that way, OK? It is a betrayal, OK? He is essentially double-crossing — not just double-crossing President Trump, but the other members of the G-7, who were working together and pulling together this communique," Kudlow said.

"President Trump played that process in good faith," he continued. "So, I ask you, he gets up in the airplane and leaves. And then Trudeau starts blasting him in a domestic news conference? I'm sorry. It is a betrayal. That is a double-cross."

At the news conference, Trudeau said it was "kind of insulting" that the U.S. implemented tariffs on the basis of national security. He pledged to impose retaliatory tariffs against the U.S., adding Canada "will not be pushed around."

Navarro, Trump's top trade adviser, in an appearance on Fox News, declared Trudeau's comments "one of the worst political miscalculations of a Canadian leader in modern Canadian history."

"There's a special place in hell for any foreign leader that engages in bad faith diplomacy with President Donald J. Trump and then tries to stab him in the back on the way out the door," Navarro said on "Fox News Sunday."

Trudeau, at least initially, did not respond to the backlash directly. However, Canada's foreign minister, Chrystia Freeland, said the comments were not "particularly appropriate or useful."

"Canada does not believe that ad hominem attacks are a particularly appropriate or useful way to conduct our relations with other countries,” Freeland said at a press conference Sunday.

Tensions between the U.S. and Canada have been on the rise in recent weeks after Trump vowed to implement tariffs on steel and aluminum imports. He ended Canada's exemption from those tariffs, citing national security concerns.

In the days leading up to the G-7 meetings, Trump set his sights on Trudeau, accusing the prime minister of “being so indignant” in voicing his concerns with U.S. trade policy. He argued Canada has imposed harsh tariffs of its own on dairy imports.

Kudlow and Navarro asserted that Trudeau's comments were particularly troubling given the timing.

Trump is set to meet Tuesday morning in Singapore with the North Korean leader.

Kudlow acknowledged Trump's reaction to Trudeau's comments was "in large part" about the meeting with Kim.

"POTUS is not going to let a Canadian prime minister push him around," he said. "Kim must not see American weakness."

"And this is a case where Trudeau — it was like, I don't know, pouring collateral damage on this whole Korean trip," he continued. "Trudeau made an error. He should take it back. He should pull back on his statements and wish President Trump well in the Korea negotiations."

Trump did Trudeau a "courtesy" by attending the G-7 summit in Quebec, even when he had "bigger things on his plate in Singapore," Navarro said Sunday.

"He did him a favor and he was even willing to sign that socialist communique," he said. "And what did Trudeau did — do as soon as — as soon as the plane took off from Canadian airspace, Trudeau stuck our president in the back. That will not stand."

Democrats contended on Sunday that Trump's actions and comments harmed long-standing relationships with U.S. allies.

In addition to his decision to double down on tariffs, prompting concerns of a global trade war, Trump suggested Russia should readmitted to the G-7. Member countries decided to expel Russia in 2014 after it annexed Crimea from Ukraine.

Sen. Ed Markey Edward (Ed) John MarkeyDemocrats shoot down talk of expanding Supreme Court Schumer: 'Nothing is off the table' if GOP moves forward with Ginsburg replacement Democrats see fundraising spike following Ginsburg death MORE (D-Mass.) said on CBS's "Face the Nation" that Trump is "driving our allies away."

Sen. Dianne Feinstein Dianne Emiel FeinsteinFeinstein 'surprised and taken aback' by suggestion she's not up for Supreme Court fight Democrats shoot down talk of expanding Supreme Court Biden leads Trump by 12 points among Catholic voters: poll MORE (D-Calif.) lamented that Trump made a "big mistake" in not signing onto the communique at the conclusion of this year's summit.

"We don't want to stand alone in the world. We need to stand with our democratic allies," she said on CNN. "Now, will there be differences of opinion, will we not like a statement that one or the other makes? Of course. But that doesn't mean you reject what the G-7 stands for and just move out and ignore it."

— Updated at 1:52 p.m.