U.S. President Donald Trump has Canada in his sights once again, this time threatening to impose a 50 per cent tariff on all Canadian-made aircrafts sold to the U.S. In a social media post, Trump says the tariff will come into effect if Canada doesn't immediately certify business jets made by American planemaker, Gulfstream and that the U.S. will decertify all aircrafts made in Canada, including Bombardier. Joining us with more is John Gradek, aviation expert at McGill Unviersity.