Former FBI Director James Comey tweeted his support for Canada late Saturday after President Trump attacked Canadian Prime Minister Justin Trudeau.

"Our national security relationship with Canada is vital and saves American lives. It was built over generations and is bigger than any person or dispute. This too shall pass," Comey tweeted, including a photo of him at Canada's Parliament Hill.

Comey has been highly critical of Trump since the president fired him last year, including in his new book "A Higher Loyalty: Truth, Lies, and Leadership."

Trump attacked Trudeau in a pair of tweets Saturday after leaving the Group of Seven (G-7) summit, claiming that Trudeau made "false statements" at a news conference and calling the prime minister "very dishonest and weak."

Trump also said the U.S. would not endorse the joint communique signed by the other G-7 member countries, after Trudeau had said all countries signed it, and appeared to threaten more tariffs against Canada.

The Canadian leader had said at a press conference that his country wouldn't be "pushed around" by the U.S. over Trump's recent decision to impose stiff tariffs on steel and aluminum imports from the nation.