Minutes after the publication of a joint communique that was approved by Trump and other Group of Seven leaders at a summit in the city of Quebec, the United States leader announced on Twitter that he was retracting his support.
The Canadian prime minister's office responded to Trump's tweets accusing Trudeau of "false statements" on Saturday, saying that the Prime Minister said nothing during the G7 summit that he had not said previously.
"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.
American tariffs are in response to Canada's tariffs of "270% on diary" delivered by the USA, he said.
Italy's new anti-elite Prime Minister Giuseppe Conte played by the rules at the Group of Seven industrialized nations summit, leaving none of the club's members unhappy in his debut on the worldwide stage in Canada.
French President Emmanuel Macron said Europe put up a united front at the summit, also attended by the leaders of Britain, Italy, Germany and Japan.
"International cooperation can't depend on anger and small words".
Before Trump's turnaround, British Prime Minister Theresa May, who Trump snubbed at the summit, strove to reinforce the image of the "special" US-UK relationship.
Trudeau said he told Trump in candid conversations that USA steel and aluminum tariffs imposed this month were "insulting" and that Canada will move forward with counter-tariffs.
Rafael Nadal beats Dominic Thiem for his 11th French Open title
Those who should be anxious are the likes of world number three Alexander Zverev, who again flattered to deceive in Paris. It also intensified the headache facing tennis' highly-rated but woefully under-performing next generation.
Trump says National Basketball Association champs won't get White House invite
The president's comments came during an exchange with reporters at the White House before departing for the G-7 summit in Ontario. It will be interesting to see how the players react to Trump's proposal.
Dominic Thiem awaits as Rafael Nadal eyes 11th title in Paris
These two have played nine times and Nadal has won six of those matches. 'Thiem has shown in Madrid two weeks before. If you listen to Thiem's coach, Gunter Bresnik, his chances of winning are akin to landing a million dollar jackpot.
"It's going to change", he said.
Vice President Mike Pence told Trudeau he would have to agree to that before Trump would agree to meet him. The president had described the G7 meeting as cordial, even though he accused the US allies of treating America "like a piggy bank".
Ontario premier-designate Doug Ford is also among those setting aside his political differences with Trudeau, re-asserting today that he stands "shoulder to shoulder" with the prime minister on trade. We have seen this with the climate agreement or the Iran deal.
Trump was reacting to comments made by Trudeau on Saturday in which he threatened to torpedo negotiations on a new NAFTA deal if the Americans did not remove tariffs on Canadian steel and aluminum.
Although Canada and Mexico say the idea is unworkable, Trump told reporters earlier on Saturday that the new deal would contain such a provision.
Trump turned heads last week by slapping steel and aluminum tariffs on Canada and the E-U, provoking retaliation and widespread worry of a brewing trade war...and he didn't let up.
"The world as we know it, namely the USA -led rules-based multilateralism, is now in serious danger of unraveling, as illustrated at the G7 meeting", said Erik Nielsen, chief economist at Unicredit Bank.
Macron, who signaled closer ties with Trudeau ahead of the summit, rebuked Trump and likened him to a rogue leader.
British Prime Minister Theresa May "is fully supportive" of Trudeau and his leadership, a senior United Kingdom government source said, while European Council President Donald Tusk tweeted: "There is a special place in heaven for @JustinTrudeau".