It was an unprecedented attack on the leader of the USA neighbour and ally.
He described all seven leaders coming together to sign the joint declaration despite having "some strong, firm conversations on trade, and specifically on American tariffs".
The statement that Trump reneged on was also signed by the heads of government of Britain, Canada, France, Germany, Italy and Japan, all of which have also been hit by the United States tariffs of 25 percent on imported steel and 10 percent on aluminum.
A picture of US President Donald Trump and German Chancellor Angela Merkel displaying less-than-friendly body language has turned out to be a defining image of the contentious meeting of the G7 leaders of the world's advanced economies.
As Trudeau said after the blowup, the sentiments were nothing he hadn't previously made clear in public - he has been clear that Canada will fight back against Trump's punitive trade measures, after a failed strategy of appeasing the president.
France and Europe are 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".
Asked about Trump's tweets and the future of the G7 late Saturday during a photo op in La Malbaie, Trudeau declined to respond to several questions.
Donald Trump and Justin Trudeau have been at loggerheads over trade tariffs
Russian Federation was thrown out of the group in 2014 over the annexation of Crimea.
"That's going to be a priority", Ford said.
The French president, Emmanuel Macron, stands next to Merkel, partially obscured, with the British prime minister, Theresa May, more obscured still at his right. But the president broadsided his allies after leaving the meeting by disavowing a joint statement the USA had agreed to, criticizing Trudeau and vowing tariffs on automobiles. "Our Tariffs are in response to his of 270 percent on dairy!" the USA president tweeted. "Very dishonest & weak", he said of Trudeau.
Investors are also concerned about the future of the North American Free Trade Agreement, which Trump has threatened to terminate.
In recent weeks, trading partners of the USA have criticised new tariffs on steel and aluminium imports imposed by the Trump administration.
"These are jointly shared principles, although the pitfalls lie in the details", she said in a press conference, adding that she expected a joint G7 statement on trade would be issued at the end of the summit. "Will there be differences of opinion, will we not like a statement that one or the other makes?"
Mr Macron's office said France and other European Union countries would maintain their support for the final G7 communique.
A German government spokesman also said that Berlin stands by the jointly agreed G7 communique in which leaders underlined the crucial role of a rules-based global trading system and promised to fight protectionism. The measure hits European Union trading partners even though the main target is overcapacity at state-backed Chinese producers, who Europe and the USA have long complained have flooded markets with cheap steel.More news: Aletta, first 2018 hurricane, reaches Category 4 near Mexico
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