Washington DC - President Donald Trump on Thursday said all Canadian-built aircraft would lose their US certification until Canada approves American-made Gulfstream business jets, a stunning move threatening major travel disruptions if enacted.

Writing on Truth Social, Trump claimed that "Canada has wrongfully, illegally, and steadfastly refused" to grant certification to Gulfstream's newest models – the 500, 600, 700, and 800.

"We are hereby decertifying their Bombardier Global Expresses, and all Aircraft made in Canada, until such time as Gulfstream, a Great American Company, is fully certified, as it should have been many years ago," he said.

He additionally threatened a 50% tariff on all Canadian aircraft sold to the US.

It was not immediately clear how Trump could unilaterally decertify aircraft or what that would entail.

The US Department of Transportation and Federal Aviation Administration referred questions to the White House, which did not immediately respond to AFP's requests for comment.

Quebec-based Bombardier said in a statement that it had "taken note of the post" and was "in contact with the Canadian government."

"Thousands of private and civilian jets built in Canada fly in the US every day. We hope this is quickly resolved to avoid a significant impact to air traffic and the flying public," the company added.

While the Global Express is a business jet, Trump's threat to decertify "all" Canadian aircraft would also appear to include CRJ regional jets and Airbus A220s – used by several major US airlines for shorter range flights.

The move is the latest in a string of verbal and economic attacks on Canada since Trump's return to power last year.

Earlier in the week, Trump threatened Canada with 100% tariffs after Prime Minister Mark Carney traveled to China and struck several economic deals.

Canada has been hit hard by Trump's sectoral tariffs – especially in the auto, steel, and aluminum sectors – but more than 85% of bilateral US-Canada trade has remained tariff-free through the ongoing trade war.

Carney has enjoyed better ties with Trump, compared to his predecessor Justin Trudeau, whom Trump often referred to as a "governor" of what he declared should be the 51st US state, but their relationship has soured in recent days.

The Canadian premier delivered a blistering denunciation of US global leadership at last week's World Economic Forum in Davos, earning a rare standing ovation and capturing global headlines.

Trump shot back in his own Davos address, telling Carney to watch his words, as "Canada lives because of the United States" and later referring to Carney as a "governor" in a social media post.