Trump’s move deepens a rift between two North American countries that have suffered a debilitating blow to their decades-old alliance.

Major stock indexes were slightly lower on Friday as U.S. President Donald Trump's announcement of tariffs on imports from Canada fanned worries about trade tensions, with the Canadian dollar down against the greenback.

Canada faces another set of tariffs in its ongoing trade talks with the U.S. However, in this latest round of tariff announcements, investors have learned to largely tune them out as negotiating bluster rather than policy commitments.