If implemented, Trump's new 35 percent duties will be "separate from all Sectoral Tariffs," such as the 50 percent tariff on steel and aluminum imports. Trump also promised that, if Canada raises its own tariffs in response, then "whatever number [Canada chooses] to raise them by, will be added onto the 35% that [the U.S. charges]."

Trump, 79, notified Canadian Prime Minister Mark Carney of the incoming tariffs in a letter – one of dozens the president has fired off to foreign leaders this week ahead of an Aug. 1 deadline for

Donald Trump surprised markets late Thursday with a letter announcing a 35% tariff on Canadian goods, but some notable industries such as energy could get some relief from the new threat.

The deadline for the duties to go into effect are still three weeks, which may mean the announcements could be a negotiating move.