What the Certification Dispute is AboutBehind the headlines is a technical but strategically important issue: aircraft certification. A 50 per cent tariff on Canadian aircraft imports could dramatically raise costs for US buyers, disrupt existing contracts, and potentially lead to retaliatory measures. The tariff threat against Canada follows recent warnings of sweeping tariffs on other Canadian imports and criticism of Canadian trade diversification efforts. In recent months, Trump has levied other tariff threats related to Canadian trade deals with third countries and broader geopolitical disagreements. What is clear, however, is that a dispute rooted in aircraft certification has morphed into a significant diplomatic flashpoint.