President Donald Trump said on Thursday that he is decertifying all aircraft made in Canada and threatened a 50% tariff on those planes until American-made Gulfstreams are certified in that country.

President Trump deepened his rift with Canada on Thursday, threatening to restrict the use of Canadian-built aircraft in the United States because of a dispute related to American-made business jets.

That threat, if carried out, would have a drastic impact on U.S. carriers like American Airlines (AAL.O) and Delta Air Lines (DAL.N), which rely on Canadian-made airplanes for many of their regional s...