Although Trump said the tariffs are necessary to protect US industry and workers, Canada and the European Union have denounced them as illegal and are preparing retaliation, raising the prospect of a tit-for-tit escalation.
At one point, Macron waxed on about the apparent negative effect of USA hegemony, and suggested nothing short of sheer human mortality and the sweep of history would undo Trump's decision to dump the climate accord that was struck in the French capital nearly three years ago. German Chancellor Angela Merkelsaid they were "illegal", while Trudeau said they were "insulting and totally unacceptable".
"The American President may not mind being isolated, but neither do we mind signing a six country agreement if need be", Macron tweeted.
Trump, who met with Japanese Prime Minister Shinzo Abe in Washington before the summit, may be more preoccupied with next week's historic nuclear summit with North Korean leader Kim Jong Un. But the White House has signaled no change in plans.
"There may be disagreements", Kudlow added.
Many locals say people in the region, where several generations of families have worked in aluminum production, are anxious the uncertainty caused by the tariffs could eventually lead to job losses - on both sides of the border.
Mr. Trump claims France, Canada and other nations are taking advantage of the USA on trade. It gave Trump a brief respite from criticism over the punishing steel and aluminum tariffs he has imposed on his G7 partners.
He doesn't see the USA tariffs as a specific attack against Canada or even Saguenay, but likely more of a strategic move by someone he considers a canny and experienced negotiator.
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He warned that if they didn't bear fruit, he and his supporters "fully expect" to continue pushing their petition. Lawmakers are wary of a trade war, he said, but "we're not looking for a fight with the president".
The DC paper reported that there had been discussions for several days about whether Trump might bail on the G7 and send Vice President Pence instead.
Macron, meanwhile, threatened to exclude the USA from the annual joint statement issued at the end of the G-7 summit. The member countries are: Canada, France, Italy, Japan, Germany, the United States and the Britain.
The disputes threaten to derail a meeting that Trudeau had planned, focusing on inclusive growth, gender equality and protecting oceans. After years in which Russia's wealthy were invited to base themselves in London without questions being asked about how they made their money, the Home Office is reviewing visas.
Trump showed no sign of backing down on Friday after earlier accusing both France and Canada of imposing massive tariffs on USA goods, and then accusing Canadian Prime Minister Justin Trudeau of "being so indignant".
Treasury Secretary Steven Mnuchin responded: "We believe in the G-7, it's an important group", adding that Trump looks forward to the gathering.
The increasingly critical tone from allies is a shift after leaders spent the past year and a half seeking to woo and cajole the American president. They tried to have close relations with him.
Russian Federation announced its permanent withdrawal from the G8 in 2017 at which point the group was renamed the G7.
Canada levies a 270 per cent tariff on milk, 245 per cent on cheese and 298 per cent on butter, in an effort to keep USA and foreign dairy imports out.
Cherry, who runs the Aluminium Valley Society, also said that because 80 per cent of Canadian aluminum is shipped to the USA the tariffs don't make any sense for anyone.