Trump’s Tariffs on Steel and Aluminum Take Effect

President Trump’s sweeping tariffs on foreign steel and aluminum went into effect on Wednesday, escalating America’s trade spats with global competitors, including close allies already reeling from his on-and-off approach to trade penalties.

Mr. Trump’s tariffs of 25 percent on the metals hit imports that enter the United States from any country in the world. The move, which many domestic steel and aluminum makers support, is expected to raise costs for American manufacturers of cars, tin cans, solar panels and other products, potentially slowing the wider U.S. economy.

The action on metals was just the latest attempt by Mr. Trump to leverage the power of tariffs and the American market against foreign governments. Last week, he issued steep tariffs on imports from Canada, Mexico and China, blaming those countries for the entry of drugs and migrants into the United States, before quickly paring some of them back. The president is threatening to impose a raft of other tariffs, including on foreign cars and against countries that he says discriminate against the United States.

His approach has been met with a market slump and has sent many U.S. allies into a defensive mode as they try to decipher what the president actually wants. On Tuesday, Mr. Trump threatened to double the tariffs on Canadian metal after Ontario had responded to Mr. Trump’s previous tariffs by putting a surcharge on electricity exported to the United States. Within hours, Ontario had suspended its surcharge, and Mr. Trump walked back his threats.

The metal tariffs, and other levies to come, are likely to again worsen trade disputes. Foreign governments, including in Canada and Europe, have vowed to retaliate by issuing levies that will most likely hurt U.S. exporters. The metal tariffs mainly affect U.S. allies: Canada is by far the largest supplier of both steel and aluminum to the United States. Brazil, Mexico, South Korea and Vietnam are also top suppliers of steel, while the United Arab Emirates, Russia and China are top suppliers of American aluminum.

The tariffs restore and expand similar measures that Mr. Trump put in place in 2018, which ushered in several long-running trade wars. Mr. Trump argued that the tariffs were needed to protect national security and provide a reliable source of metal for the military in wartime.