Trump administration tariffs on all imported aluminum and steel are now in effect as the United States launched a 50% duty directly on those materials Wednesday.

The United States is highly reliant on steel imports, bringing in more of the material from abroad than any other country in the world, according to the International Trade Administration. More than 26 million metric tons of steel were imported last year, most of which came from Brazil, Canada, Mexico, South Korea, and China.

President Donald Trump has promised to hike nearly all of his tariffs on foreign steel and aluminum to a punishing 50% on Wednesday, a move that would hammer businesses from automakers to home builders,