The resurgent trade spat between U.S. President Donald Trump and Canadian Prime Minister Mark Carney comes at a delicate juncture for both North American countries - and the global economy. Missteps between the neighboring G7 nations could have wide-ranging economic impacts. The Trump administration imposed 50% tariffs on an array of Canadian goods on Saturday after bilateral talks collapsed on Friday. These levies might appear modest on the surface, applying to only 5.5% of Canada's exports to America, goods worth around $20 billion.