Canadian Prime Minister Justin Trudeau's former foreign policy adviser slammed 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 on Twitter amid Trump's recent comments tied to the Group of Seven (G-7) summit, calling the U.S. leader a "pathetic little man-child."

"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. You don’t need to be Freud. He’s a pathetic little man-child," Roland Paris said in a tweet on Saturday.

Big tough guy once he’s back on his airplane. Can’t do it in person, and knows it, which makes him feel week. So he projects these feelings onto Trudeau and then lashes out at him. You don’t need to be Freud. He’s a pathetic little man-child. https://t.co/lpz0R5Ftyj — Roland Paris (@rolandparis) June 9, 2018

Paris was responding to a tweet from Trump in which he said the U.S. would not sign the G-7 communique, despite the Canadian leader's previous comments.

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"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!" the president said.

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! — Donald J. Trump (@realDonaldTrump) June 9, 2018

Trudeau had said earlier that all of the G-7 members had agreed to sign the statement during the summit in Quebec.

The prime minister's office pushed back against the president on Saturday, saying Trudeau had been consistent with Trump during the summit.

"The Prime Minister said nothing he hasn’t said before — both in public, and in private conversations with the President," the Prime Minister's Office said in a statement.

Canadian Foreign Minister Chrystia Freeland responded to the attacks from the U.S. on Sunday, saying Canada did not find the rhetoric "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.