Trump tweeted: "PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that, "US Tariffs were kind of insulting" and he "will not be pushed around".
Canadian Prime Minister Justin Trudeau called USA metal tariffs "insulting" and announced retaliatory measures.
Canadian Prime Minister Justin Trudeau is greeted by President Donald Trump prior to holding talks at the White House in Washington, D.C., February 13, 2017.
Despite the apparent acrimony, it is likely that the G7 - which groups the United States, Canada, Great Britain, France, Italy, Germany and Japan - will issue a final communique at the end of the summit, a diplomatic source said.
British Prime Minister Theresa May said the other G7 leaders registered their "deep disappointment at the unjustified decision by the U.S." on its closest allies. "As the president said, reduce these barriers, in fact go to zero, zero tariffs, zero non-tariff barriers, zero subsidies, and along the way we're going to have to clean up the global trading system".
"We have a very really good relationship, very special" - Trump insists he's still best buddies with Emmanuel Macron after his latest no-holds barred handshake with the Frenchman. Re-admitting Russian Federation to the group would be an "asset", according to the president.
"I highlighted directly to the president that Canadians did not take it lightly that the United States has moved forward with significant tariffs", said Trudeau.
Trump Calls Justin Trudeau 'Very Weak And Dishonest'
Trump came out swinging in his news conference, repeating his view that America has always been cheated by its friends.
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Trump called the summit a "one time shot" for Kim, but expressed optimism at the beginning of talks with the North Korean regime. Canada and Mexico, the other members of the 1994 pact, have been frustrated by the slow pace of talks to renegotiate NAFTA.
Senate Introduces Bill that Restricts Trump's Tariff Power
Why are Republicans supporting a bill against their Republican president? They hurt American workers, families, and employers. A lot of the worry from congressional Republicans is about the instability the tariff policy could lead to.
"As Bismarck used to say, if we explained to people how sausages were made, it is unlikely they'd keep eating them", Mr Macron said.
Fears of a looming trade war were heightened last week after all the G7 nations announced plans to retaliate against Trump's tariffs with tariffs of their own. Trump has also maintained his stance that tariffs are a national security issue, because unfair trade deals "affect our military", he said.
But in a tweet after flying out of Canada, the U.S. president showed he was in no mood to back down in any trade dispute.
"We're either going to have NAFTA in a better negotiated form or we're going to have two deals", the USA president said. "The Prime Minister said nothing he hasn't said before - both in public, and in private conversations with the President", the statement said, according to the CBC.
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.
"The plan was, if Trump asked about an after party, we were going to be, like, 'Ask Angela Merkel, ' " Macron said. "The American President may not mind being isolated, but neither do we mind signing a 6 country agreement if need be", Macron wrote. But in 2014, Russian President Vladimir Putin alarmed world leaders after moving troops into eastern Ukraine and taking over Crimea.
Macron called a meeting Friday with German Chancellor Angela Merkel, British Prime Minister Theresa May, new Italian Premier Giuseppe Conte and top European Union officials just before the G-7 opening.