A war of words has erupted between the US and its G7 allies, hours after the group had put on a show of unity at the end of a tense summit.
US President Donald Trump and two of his advisers lashed out at Canadian PM Justin Trudeau, accusing him of engaging in "bad faith diplomacy".
Mr Trump retracted his endorsement of the G7's joint communique - drawing a strong rebuke from France and Germany.
That statement had sought to overcome deep disagreements, notably over trade.
In recent weeks, trading partners of the US have criticised new tariffs on steel and aluminium imports imposed by the Trump administration.
So how did the latest spat unfold?
In a news conference after the summit, the Canadian leader reasserted his opposition to the US tariffs, and vowed to press ahead with retaliatory moves on 1 July.
"Canadians are polite and reasonable but we will also not be pushed around," he said.
Mr Trump responded by tweeting en route to his next summit, in Singapore, that he had instructed US officials "not to endorse the communique as we look at tariffs on automobiles".
He said the move was based on Mr Trudeau's "false statements... and the fact that Canada is charging massive tariffs to our US farmers, workers and companies".
His top economic adviser Larry Kudlow and trade adviser Peter Navarro then took to the Sunday morning news shows to further attack Mr Trudeau.
"He really kind of stabbed us in the back," Mr Kudlow said, while Mr Navarro said: "There is a special place in Hell for any leader that engages in bad faith diplomacy with President Donald J Trump and then tries to stab him in the back on the way out the door."
Mr Trudeau's office responded by saying he had "said nothing he hasn't said before - both in public, and in private conversations with the president" and vowed to abide by the G7 final communique.
Other G7 partners also seemed stunned by Mr Trump's reaction, and pledged to support the communique.
French President Emmanuel Macron said "international co-operation cannot be dictated by fits of anger and throwaway remarks".
"Let's be serious and worthy of our people. We make commitments and keep to them," a statement from the French presidency quoted by AFP news agency said.
German Foreign Minister Heiko Maas said: "In a matter of seconds, you can destroy trust with 280 Twitter characters."
What is in the joint communique?
In the communique after the summit in La Malbaie, Quebec province, the group of major industrial nations - Canada, the US, the UK, France, Italy, Japan and Germany - had agreed on the need for "free, fair, and mutually beneficial trade" and the importance of fighting protectionism.
Other agreements reached include:
Russia: A joint demand that Moscow "cease with its destabilising behaviour" and withdraw its support for Syrian President Bashar al-Assad
Iran: A pledge to "permanently" ensure Tehran's nuclear programme remains peaceful
Climate: An agreement to disagree. The US refused to sign a pledge to implement the Paris climate change accord after Mr Trump announced the US would pull out of the agreement
Female education: To provide $2.9bn (£2.2bn; €2.5bn) to fund education for the world's poorest girls and women
What are the tariffs?
On 1 June, the US imposed a 25% tariff for steel and 10% for aluminium on imports from the European Union (EU), Canada, and Mexico. Mr Trump said the move would protect domestic producers that were vital to US security.
The EU then announced retaliatory tariffs on US goods ranging from Harley-Davidson motorcycles to bourbon. Canada and Mexico are also taking action.
What is the G7?
It is an annual summit bringing together seven major industrialised nations which represent more than 60% of global net worth between them.
Economics tops the agenda, although the meetings now always branch off to cover major global issues.
Russia was suspended from the group - then called the G8 - in 2014 because of its annexation of Crimea from Ukraine.
On Friday, Mr Trump made a surprise call for Moscow to be readmitted but German Chancellor Angela Merkel said other members were against the idea.