President Donald Trump signed a directive on Tuesday raising steel and aluminum tariffs to 50% from 25% starting on June 4, following through on a pledge to boost import taxes to help domestic manufacturers.

Trump cast the move, which takes effect at 12:01 a.m. Wednesday as necessary to protect national security.

The order said the previous charge had “not yet enabled” domestic industries “to develop and maintain the rates of capacity production utilization that are necessary for the industries’ sustained health and for projected national defense needs.”

“Increasing the previously imposed tariffs will provide greater support to these industries and reduce or eliminate the national security threat posed by imports of steel and aluminum articles and their derivative articles,” reads the order, which the White House posted on X.

US President Donald Trump arrives at the US Steel Corporation Irvin Works facility in West Mifflin, Pennsylvania, US, on Friday, May 30, 2025.

Metals tariffs on imports from the UK will remain at the previous 25% rate to allow the two nations to work on new levies or quotas by a July 9 deadline, according to the order.

A key component of the nations’ framework reached last month was an effort to lower trade barriers on steel, though the two sides did not agree on the extent of relief for British steel and the deal has yet to take effect.

Trump’s decision fans trade tensions at a time when the US is locked in negotiations with numerous trading partners over his so-called “reciprocal” duties before a July 9 deadline.

The president’s ability to unilaterally impose tariffs stands on shakier legal ground, after a federal court last week knocked down many of his other duties put into place under an emergency law.

His levies on metals were not subject to that ruling, however, and the president has sought to show he’s undeterred from hiking tariffs and demanding countries make offers at the negotiating table.

Trump announced the decision during a speech at a United States Steel Corp. plant in Pennsylvania last Friday, where he endorsed the sale of the company to Japan’s Nippon Steel Corp. while pledging that it would remain under some form of American control.

“That means that nobody’s going to be able to steal your industry,” he told steelworkers. “It’s at 25%, they can sort of get over that fence; at 50% they can no longer get over the fence.”

He later announced in a social media post that the aluminum tariff would also rise to the same level.

Trump’s administration is locked in a legal battle over the bulk of its tariffs, imposed under the International Emergency Economic Powers Act. The steel and aluminum tariffs are unaffected by that fight because they were imposed using a different authority.