US President Donald Trump said his administration would double duties on steel imports to 50%.
He announced the tariff hike while speaking in Pennsylvania at a US Steel plant, where he also touted a "partnership" between the American steelmaker and Japan's Nippon Steel.
"We're going to bring it from 25% to 50%, the tariffs on steel into the United States of America, which will even further secure the steel industry," he said. "Nobody's going to get around that."
The move puts further pressure on global steel producers and threatens to deepen Trump's trade war and increase market uncertainty over Trump's disorienting tariff regime.