President Donald Trump signed proclamations on Monday imposing 50% tariffs on most Canadian goods, saying the action was a response to what his administration described as Canada's discriminatory treatment of U.S. automobiles, alcohol and dairy products. The tariffs, which are scheduled to take effect in 30 days, were issued under Section 338 of the Tariff Act of 1930, a provision that has rarely been used in modern trade policy. Administration officials said the measures will apply to many products that had previously entered the United States duty-free under the United States-Mexico-Canada Agreement, although energy products, potash, fish and critical minerals are exempt.

The announcement marks a significant escalation in trade tensions between the two countries, whose economies are among the world's most integrated. Canadian Prime Minister Mark Carney said his government remains committed to negotiations but rejected allegations that Canada has treated U.S. products unfairly. Canadian officials have indicated they are reviewing possible responses, while business groups on both sides of the border warned that additional tariffs could disrupt supply chains, increase costs for manufacturers and consumers, and create further uncertainty for industries that rely on cross-border trade.