After all, just two weeks ago, Treasury Secretary Steven Mnuchin declared the trade war was "on hold", setting off a celebration on Wall Street.
"They are relying on the overwhelming strength of the U.S.to compel a much weaker neighbour to give in to whatever they demand, " Bothwell said.
Trump's concerns are said to be based on the fact that other leaders who are attending the summit disagree with him on key issues and he "does not want to be lectured by them".
Trudeau's courting of Trump appeared to work for a time.
But rather than seek a fight with Trump at the summit, French President Emmanuel Macron made an appeal for productive discussion. The announcement came as talks stalled between the U.S., Canada and Mexico over renegotiating the 1994 North American Free Trade Agreement.
European Union and Canadian leaders also appeared ready to unite against Trump at the upcoming G7 summit.
Canadian Prime Minister Justin Trudeau's position on the punitive measures would remain "consistent and clear" during talks at the summit, the official said.
G-7 leaders are meeting Friday and Saturday in what's shaping up to be the most divisive gathering of leaders from major industrialized nations in years.
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The G7 groups Canada, the United States, Japan, Britain, Italy, France and Germany.
Under Trump, the United States has abandoned its traditional role in the G-7.
Adding to the uncertainty is European anger over Trump's decision to pull the United States out of the worldwide nuclear agreement with Iran.
"The six countries of the G7 without the United States, are a bigger market taken together than the American market", Macron said.
President Trump tweeted Friday morning: "Looking forward to straightening out unfair Trade Deals with the G-7 countries".
Top White House economic advisor Larry Kudlow opposed tariffs before joining Trump's team, but now says he agrees the trade status quo hurts America. Let them meet; let them discuss.
Last night she called from restraint from the European Union, which is set to unveil its own list of tariffs on USA exports in retaliation. European allies have urged Trump to reconsider.
The Trudeau Government is scoffing at the idea of scrapping NAFTA negotiations in favour of separate bilateral trade deals.
At last year's summit in Sicily, Mr Trump would not agree to sign a closing statement on climate change and withdrew the USA from the Paris agreement days later.
Sebastian Mallaby, a senior fellow with the Council on Foreign Relations, described the relationships between the US and the rest of the G-7 as at a "new level of crisis", saying that it was not just about trade but "a general USA attitude toward the system".