"We hope it doesn't come to that, but if the USA tariffs remain in effect, we will impose our tariffs on July 1", he said.
Having left the G7 summit in Canada early, Mr Trump's announcement on Twitter that he was backing out of the joint communique torpedoed what appeared to be a fragile consensus on a trade dispute between Washington and its top allies.
Describing the United States tariffs on European steel and aluminium as "unjustified", she left no doubt that EU nations would impose counter-measures on United States goods in response but cautioned against tit-for-tat retaliation which might lead to a trade war.
They welcomed stranded US travelers after the 9/11 attacks; they share the longest undefended border with the USA; and they have been our allies in the modern global security apparatus that Trump now wants to blow up.
When Mr Trump's tweets withdrawing support from the G7 statement hit on Sunday, the Prime Minister's office said Mr Trudeau had not said anything in his closing news conference he has not said to the US President before.
June 7 - On the eve of the G7 summit, Trump tweets that Trudeau is "being so indignant" in bringing up the history of U.S.
"That's unconscionable", Heyman said."Anybody who represents the United States of America from the White House using that kind of language with any world leader of any type, I think is uncalled for".
"The NDP stands in solidarity with the government and the prime minister against these provocative words from the American administration", said NDP House Leader Ruth Ellen Brosseau.
Liberal MP and former dairy farmer Wayne Easter said there was a real sense of panic building in his P.E.I. riding over the implications of Trump's pronouncements following his departure from the G7 gathering.
Media captionDairy wars: Why is Trump threatening Canada over milk?
Mr Trudeau, who had said at the news conference that Canada would retaliate over new U.S. tariffs, did not respond to questions about Mr Trump when the prime minister arrived at a Quebec City hotel on Sunday for meetings with other world leaders.
Trump called Trudeau "very dishonest and weak", among other things.
- The Prime Minister's Office responds by saying Trudeau didn't say anything he didn't previously say in public and private conversations with Trump.
Trump continued tweeting Sunday evening about Trudeau, accusing Canada of making $100 billion in trade with the U.S.
The White House is quietly trying to fix the American government's fractured relationship with Canada as President Donald Trump is in Singapore to meet with North Korean leader Kim Jong-un, Politico reported Monday.