Trump’s 50% Tariffs on Steel and Aluminum Imports Go Into Effect

U.S. tariffs on steel and aluminum imports doubled on Wednesday, as President Trump continued to ratchet up levies on foreign metals that he claims will help revitalize American steel mills and aluminum smelters.

The White House called the increased tariffs, which rose to 50 percent from 25 percent just after midnight Eastern time, a matter of addressing “trade practices that undermine national security.” They were announced during Mr. Trump’s visit to a mill run by U.S. Steel last week, and appear to be aimed at currying favor with steelworkers and the steel industry, including those in swing states like Pennsylvania, where U.S. Steel is based.

The higher levies have already rankled close allies that sell metal to the United States, including Canada, Mexico and Europe. They have also sent alarms to automakers, plane manufacturers, home builders, oil drillers and other companies that rely on buying metals.

In an executive order, Mr. Trump said the higher tariffs would “more effectively counter foreign countries that continue to offload low-priced, excess steel and aluminum in the United States market and thereby undercut the competitiveness of the United States steel and aluminum industries.”

Kevin Dempsey, the president of the American Iron and Steel Institute, an industry group, praised the move. He said China and other countries oversupplied the international market, making it harder for U.S. producers to compete.

“Given these challenging international conditions that show no signs of improvement, this tariff action will help prevent new surges in imports that would injure American steel producers and their workers,” Mr. Dempsey said.