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

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.

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.

The country’s new prime minister, Mark Carney, has been called the “Trump whisperer,” and negotiations have been cordial and professional. But it’s been a wild ride.

Trump this spring imposed a 25% tariff on cars and car parts, including those from Canada. But certain cars and parts qualify for preferential treatment under the USMCA, meaning the 25% tariff applies only to the non-U.S. content of the automobile or part.

The letter reiterated Trump’s complaints about dairy quotas, fentanyl and the U.S. trade deficit, which is mostly fueled by American refineries’ thirst for Canadian oil. His social media post caused the Canadian dollar to immediately tumble, indicating the market wasn’t expecting this escalation.

Plus, the Justice Department has subpoenaed 20 doctors and clinics involved in “performing transgender medical procedures on children.”