U.S. President Donald Trump's Twitter tirade against Prime Minister Justin Trudeau following the G7 is sparking promises of support from some of Trudeau's political rivals as well as calls for calm from foreign diplomats and experts.
Trump said that Trudeau was "meek and mild" during the G7 meeting.
The announcement and Trump's planned tariffs have also put him on a collision course with Trudeau, leader of another key USA ally.
But foreign leaders publicly and pointedly rejected Trump's demands, raising the possibility of further escalation - particuarly after Trump's recently imposed tariffs on steel and aluminum from the European Union, Canada and Mexico and said doing so protected United States national security.
Italy's new anti-elite Prime Minister Giuseppe Conte played by the rules at the Group of Seven industrialized nations summit, leaving none of the club's members unhappy in his debut on the global stage in Canada.
The Group of Seven comprises seven of the largest advanced economies in the world - Canada, France, Germany, Great Britain, Italy, Japan and the United States.
"International cooperation can not depend on being angry and on sound bites". And we charge nothing, ' Trump said.
The remarks apparently upset Trump, who had left the conference early to travel to Singapore for a highly anticipated meeting with North Korean leader Kim Jong-un.
Earlier in the day, Trump said he had raised the issue of lifting trade barriers, tariffs and subsides to facilitate worldwide trade at the G7 summit.
"Trump did not want to be isolated", Macron said.
Trudeau on Saturday rejected a US demand for a sunset clause in NAFTA but said he was prepared to compromise on the issue, which is holding up talks to update the 1990s-era pact.
"So we are either going to have NAFTA in a better negotiated form or we're going to have two deals". "We're like the piggy bank that everyone is robbing, and that ends".
The relationship has reportedly frayed to the point where Trump was considering sending Vice President Mike Pence to the G7 summit in his place, according to a Washington Post report.
Trump also railed against French President Emmanuel Macron, after Macron likened him to a rogue leader.
"Canadians. stood shoulder to shoulder with American soldiers in far off lands in conflicts from the First World War onward", the prime minister said at a press conference at the end of the summit.
But the president also suddenly called for tariff-free trade among all the countries - just a week after he imposed a 10 percent tariff on aluminum and 25 percent tariff on steel from Canada, Mexico and the European Union. "We are open to dialogue, but that does not mean transforming a defined process, linked to the implementation of the Minsk accords", he said.
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 worldwide trading system and promised to fight protectionism.
Trump's closest advisers added to the attack during televised interviews on Sunday.