When Mr Trump's tweets withdrawing support from the G7 statement hit on Sunday, the Prime Minister's office said Mr Trudeau had not said anything in his closing news conference he has not said to the US President before.
Peter Navarro says his job was to send a "signal of strength" after Trudeau's post-G7 news conference sent the US president into a fit of pique that threw the summit into disarray.
On Tuesday, Trump said: "We have a big trade deficit with Canada.it's close to US$100 billion a year deal loss".
France is also standing by the G7 communique, a French presidency official said, adding anyone departing from the commitments made at the summit would be showing their "incoherence and inconsistency". "This can not be our party", Flake tweeted on Sunday.
The comments, made after Trump had left to go to Singapore for his much-anticipated meeting with North Korean leader Kim Jong Un, infuriated the USA president. "But actually, we were just talking, the whole group, about something unrelated to everything, very friendly".
Trump on Sunday arrived in Singapore, where he and Kim are to meet Tuesday to discuss that nation's nuclear arsenal.
"We finished the [G7] meeting and really everybody was happy".
Heyman said Trump's tweets and protectionist about-face could and force Canada to look for trade partners beyond the USA, noting Canada's trade frameworks with Europe and Asia.
White House economic adviser Larry Kudlow accused Trudeau of undermining Trump right before his meeting in Singapore with North Korean leader Kim Jong Un. German Chancellor Angela Merkel, who also attended the summit, told German public television that she found Trump's tweet disavowing the G-7 statement "sobering" and "a little depressing".
But Mr Trudeau's comments provoked a response from the United States president.
At the G-7 summit, Trudeau doubled down and said, "Canadians will not be pushed around".
Despite the tension between Trump, Europe and Canada, the president has emphasized what he has described as strong relations.
The Americans' criticism of Trudeau left a former Canadian prime minister, Stephen Harper, stumped.
Rolando Pablos, the secretary of state in Texas' Republican administration, brushed off questions over Trump's feud with Canada but stressed the importance of trade. "I know it was reported sort of nasty both ways - I was angry at her, or she. It is essentially double crossing", Kudlow told CNN's Jake Tapper.