He claims Canada is unfairly blocking US business jets and vows to retaliate by decertifying Canadian planes. Washington: US President Donald Trump escalated his trade confrontation with Canada on Thursday, threatening a 50% tariff on all Canadian-made aircraft and vowing to "decertify" planes from the country's top manufacturers. The threat, issued via social media, marks the latest flare-up in an intensifying feud between Trump and Canadian Prime Minister Mark Carney. In his latest ultimatum, Trump alleged that Canada has "wrongfully, illegally, and steadfastly" refused to grant safety certification to business jets produced by Georgia-based Gulfstream Aerospace. In retaliation, Trump said the US would pull the certification for aircraft built by Montreal-based Bombardier, specifically mentioning the Global Express line.