Fireworks have already started going off between President Trump and other leaders following the G7 Summit in Canada this weekend.

While aboard Air Force One on his flight from Canada to Singapore, President Trump blasted out a two-part statement on Twitter Saturday afternoon against Canadian Prime Minister Justin Trudeau.

CBS News reported on details that set off Trump’s posts:

Trudeau, who has been sparring with Mr. Trump on trade in recent days, announced at the conclusion of the G-7 summit in Canada that the retaliatory tariffs will go into effect July 1. Trudeau said he told Mr. Trump “it would be with regret but it would be with absolute clarity and firmness that we move forward with retaliatory measures on July 1, applying equivalent tariffs to the ones that the Americans have unjustly applied to us.”

“Canadians, we’re polite, we’re reasonable, but we also will not be pushed around,” Trudeau said.

President Trump tweeted in response to the situation:

Based on Justin’s false statements at his news conference, and the fact that Canada is charging massive Tariffs to our U.S. farmers, workers and companies, I have instructed our U.S. Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the U.S. Market!

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.” Very dishonest & weak. Our Tariffs are in response to his of 270% on dairy!