Mr. Trump said the decision came in response to Ontario's move to impose a 25% surcharge on electricity exports to the U.S. Mr. Trump has already imposed a 25% tariff on nearly all imports from Canada, and declared a 25% tariff rate on all steel and aluminum imports from any foreign country.

As of Monday, March 10, a Canadian plan to raise electricity costs by 25% went into effect in response to Trump’s tariffs, effective March 4. The electricity is sold to 1.5 million Americans, the Associated Press reported.