"Canadians, we're polite, we're reasonable, but we also will not be pushed around", Trudeau said.
Trump refused to sign a joint agreement with USA allies at the end of the summit and threatened to cut off trade with them unless deals were renegotiated.
Trump and North Korean leader Kim Jong-un converged on this island city state Sunday ahead of one of the most unusual and highly anticipated summits in recent world history, a sit-down Tuesday morning meant to settle a stand-off over Pyongyang's nuclear arsenal. "Kim must not see American weakness".
There is more to leadership than hosting a meeting and posing for a smiling selfie. He really kind of stabbed us in the back.
"As long-standing allies, we do not make progress by ignoring each others' concerns but rather by addressing them together", she said.
Trump's decision to withdraw his support for the communiqué has drawn sharp criticism from Germany on Sunday.
On board Air Force One, an AFP reporter was told that Trump had approved the agreement, only to be told later of the tweets.
The two-day G7 summit that began on Friday, was held in La Malbaie, Quebec province.
President Trump unloaded on Canadian Prime Minister Justin Trudeau this week; slamming the "meek and mild" leader after he publicly criticized Trump's decision to slap hefty tariffs on his nation's exports. Bob Corker has introduced legislation that would roll back the President's power to impose tariffs like the ones he introduced earlier this month on steel and aluminum on US allies, but Republican leaders don't appear eager to take it up even as an amendment to already-moving legislation.
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Mr. Trump's tweets taking aim at the leader of a country that has always been a USA ally came after the President left the G7 summit in Canada to travel to Singapore ahead of a planned diplomatic meeting with North Korean Leader Kim Jong-un, CNN reported.
TAPPER: So, this was about North Korea?
The White House is escalating its verbal attacks against Justin Trudeau, the prime minister of close American ally Canada.
Speaking on "Fox News Sunday", Navarro doubled down on Kudlow's rhetoric and said Trudeau's post-conference comments were in bad faith.
The public sniping at a sitting leader of state by White House aides shocked some veteran diplomats. So far in 2018, Canada is also the top export destination for United States goods, with over $98 billion worth of goods going over the border. "Most inept and shameless Administration since Harding".
Following the remarks by Kudlow and Navarro, Foreign Affairs Minister Chrystia Freeland is far less confrontational in an effort, perhaps, to dial things down - "In terms of the approach that governments choose to take, Canada does not believe that ad-hominem attacks are a particularly appropriate or useful way to conduct our relations with other countries".
In tweets, Trump insulted Trudeau as "dishonest" and "weak". The negotiations will either be bilateral or trilateral with Mexico, he said.
TAPPER: So, because Trudeau said that as Trump was going to Singapore. "Who picked the fight?" I said maybe in the first minute.
British Prime Minister Theresa May said on Monday that a meeting of the Group of Seven leaders in Canada had been "difficult" and that countries had to avoid taking unilateral action in order to protect the global trading system. "Well, the in-factual, the non-factual part of this was they have enormous tariffs", Kudlow said. The president could have said that.