President Donald Trump has imposed a 50% tariff on a broad range of Canadian imports, citing what he described as unfair treatment of American automobiles, dairy products and alcoholic beverages.
The tariffs will take effect in 30 days and apply to most covered goods, including products previously protected under the United States-Mexico-Canada Agreement (USMCA).
The White House said the measures are intended to protect American businesses, while exempting energy products, potash, fish and critical minerals.
The move marks a significant escalation in trade tensions between the United States and Canada, with both countries already maintaining tariffs on several key industries.
The tariffs were introduced through three presidential proclamations under Section 338 of the 1930 Tariff Act, following a Supreme Court ruling earlier this year that limited the administration's ability to impose tariffs under emergency powers.
The proclamations cite longstanding U.S. concerns over Canadian policies affecting automobiles, dairy and alcohol rather than recent disputes over wildfire smoke, despite Trump's earlier public threats linked to cross-border air quality.
Trump argues that Canada unfairly taxes certain U.S. motor vehicles and automotive parts outside USMCA rules, maintains a supply management system that restricts dairy imports through high tariffs, and continues a widespread boycott of American alcoholic beverages across most Canadian provinces.
The new duties also build on existing U.S. tariffs covering Canadian steel, aluminum, copper, softwood lumber and some automotive parts, while Canada maintains counter-tariffs on selected American steel, aluminum and vehicle imports.
Canadian officials did not immediately respond, although Ontario Premier Doug Ford said Canada should answer "tariff for tariff, dollar for dollar" if the measures proceed.
Candace Laing, head of the Canadian Chamber of Commerce, described the decision as "regrettable" while urging both governments to use the 30-day period before implementation to advance formal negotiations.
Industry groups on both sides of the border also called for a negotiated settlement to restore market access and avoid further economic disruption.
The White House said the delayed implementation provides time for discussions, but the measures signal a further deterioration in trade relations between the two neighboring economies as negotiations continue.