Trump imposes steel, aluminum tariffs on U.S. Allies and Europe plans to retaliate. President Trump followed through on a threat to impose steep metal tariffs on U.S. Allies Thursday, a long-promised decision that could spark retaliatory trade barriers on a host of U.S. Products. Commerce Secretary Wilbur Ross said that Canada, Mexico and the European Union would be subject to a 25% tariff on steel and a 10% tariff on aluminum beginning at midnight. Other countries, including Argentina and Brasil, agreed to limit metal exports. The European Union said it would respond quickly. Ref. USAToday.