Trump threatened to decertify Canadian aircraft and impose a 50% tariff, accusing Canada of unfairly blocking certification of Gulfstream business jets. Summary:President Donald Trump accused Canada of unfairly blocking certification of Gulfstream jets. He threatened a 50% tariff on all aircraft sold into the US from Canada if the issue is not resolved. US President Donald Trump escalated trade tensions with Canada after accusing Ottawa of unfairly blocking the certification of US-made Gulfstream business jets, threatening retaliatory measures that could significantly disrupt the North American aircraft market. Canada is home to Bombardier, a major global producer of business jets, while Gulfstream Aerospace is one of the US’s flagship aerospace exporters.