The United States and its Western allies have swung into a war of words and threats, risking a diplomatic and trade crisis, after US President Donald Trump abruptly rejected a previously agreed joint statement in the wake of a fractious Group of Seven (G7) summit in  Canada.

Minutes after the publication on Saturday of a communique that was approved by the leaders of seven of the world’s most advanced economies – US, France, Germany, Japan, Britain, Italy and Canada – Trump announced on Twitter that he was retracting his support, which led to a series of tense remarks among the allies.

In a flurry of tweets from Air Force One, en route to Singapore for a historic summit with North Korean leader Kim Jong-un on Saturday, Trump accused Justin Trudeau, Canada’s prime minister and host of the G7 summit, of being “very dishonest”.

He was reacting to Trudeau’s declaration that Canadians would “not be pushed around” and would hit back at punishing US tariffs on metal imports with “equivalent tariffs”.

Trudeau also called the fact that the US had based the tariffs on a national security reason “kind of insulting”.

On Sunday, White House economic adviser Larry Kudlow accused Canadian Prime Minister Justin Trudeau of betraying Trump with “polarising” statements on trade policy that risked making the US leader look weak ahead of his meeting with  Kim.

“[Trudeau] really kind of stabbed us in the back,” Kudlow said on CNN.

US trade adviser Peter Navarro echoed the same sentiment, telling Fox News that “there is a special place in hell for any leader that engages in bad faith diplomacy with President Donald J. Trump”.

Canadian Foreign Minister Chrystia Freeland responded to the comments by saying that Canada will retaliate to US tariffs in a measured and reciprocal way and it will always be willing to talk.

“Canada does not conduct its diplomacy through ad hominem attacks … and we refrain particularly from ad hominem attacks when it comes from a close ally,” Freeland told reporters in Quebec City on Sunday.

‘Fits of anger’

Earlier on Sunday, France warned that “fits of anger” cannot not dictate international cooperation.

“We spend two days working out a (joint) statement and commitments. We are sticking to them and whoever reneges on them is showing incoherence and inconsistency,” President Emmanuel Macron‘s office said on Sunday in a statement to AFP news agency.

“Let’s be serious and worthy of our people. We make commitments and keep them,” the presidency said, adding that “France and Europe maintain their support for this (G7) statement”.

German Chancellor Angela Merkel said EU will implement counter-measures against US tariffs on steel and aluminium, voicing regret about Trump’s abrupt decision to withdraw support for the communique.

“The withdrawal, so to speak, via tweet is of course … sobering and a bit depressing,” Merkel said in an ARD television interview following the G7 summit in Canada.

The Trump administration confirmed on May 31 it would apply additional tariffs on steel and aluminium imports from Canada, Mexico and European Union countries, ending a two-month exemption period.

In response, Canada, Mexico and the EU said they were putting in place their own retaliatory measures.

Allies will retaliate

The now-rejected communique acknowledged the importance of “free, fair and mutually beneficial trade and investment”.

“We strive to reduce tariff barriers, non-tariff barriers and subsidies,” it said.

“This year’s G7 meeting is already going down as the G6 + 1, with six members on one side and President Trump on the other,” Al Jazeera’s John Hendren, reporting from Quebec, said.

“A meeting six of the leaders hoped would end by de-escalating a budding trade war ended up accelerating it.”