U.S. President Donald Trump is threatening to slap a 50 per cent tariff on Canadian aircraft and says his administration will “decertify” those planes, mentioning a series of jets by aerospace company Bombardier by name.

In a post on his social media site, Truth Social, Trump justified his latest trade war escalation by accusing Ottawa of blocking the certification of a series of jets made by U.S.-based Gulfstream.

“Based on the fact that Canada has wrongfully, illegally and steadfastly refused to certify the Gulfstream 500, 600, 700 and 800 Jets, one of the greatest, most technologically advanced airplanes ever made, 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,” the president wrote.

“Canada is effectively prohibiting the sale of Gulfstream products in Canada through this very same certification process. If, for any reason, this situation is not immediately corrected, I am going to charge Canada a 50% Tariff on any and all Aircraft sold into the United States of America.”

It is unclear what he means by “decertifying” the planes, but the Federal Aviation Administration (FAA), run by a Trump appointee, is responsible for certifying aircraft to operate in U.S. airspace.