President Donald Trump threatened to decertify Canadian-made aircraft and impose a 50% tariff unless Canada approves Gulfstream jets, accusing Ottawa of illegally blocking certification while allowing its own planes access to the American market. The dispute centers on aircraft certification, a regulatory process that determines whether planes can be sold and operated in a country. Trump has accused Canadian authorities of using that process to restrict U.S.-made Gulfstream jets.”Based on the fact that Canada has…