(The Hill) – President Trump’s steel and aluminum tariffs doubled on Wednesday to 50 percent, in a dramatic move aimed at protecting U.S. industries that economists say could increase prices for American consumers.

The tariff hike on foreign metals went into effect just after midnight on Wednesday, and they apply to nearly all imports of steel and aluminum. The United Kingdom is exempt from the tariff hike — and will continue to face a 25 percent tariff rate — because of the trade deal announced by Trump and British Prime Minister Keir Starmer last month.

Trump on Friday announced plans to hike tariffs on foreign steel and aluminum imports from the 25 percent rate that has been in effect since March 12 — when Trump’s steel exemptions on tariffs expired and his import tax hike on aluminum imports took effect.

He told steelworkers in a speech at U.S. Steel’s Mon Valley Works–Irvin Plant in Pittsburgh late last month that the increase “will even further secure the steel industry in the U.S.” The president reiterated that sentiment about aluminum imports later that day.

Trump formalized the tariff hike in a proclamation on Tuesday, saying the increase would ensure “such imports will not threaten to impair the national security.”

“In my judgment, the increased tariffs will 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,” he wrote in the proclamation.

The anticipated bump in metal duties drew criticism from U.S. foreign trading allies.

Canada — the largest exporter of steel and aluminum to the U.S. — called the move “unlawful and unjustified.”

“Canada’s new government is engaged in intensive and live negotiations to have these and other tariffs removed as part of a new economic and security partnership with the United States,” Canadian Prime Minister Mark Carney’s office said in a statement.

Mexico reportedly plans to ask the Trump administration for an exemption from the steel tariff hike.

“It’s not fair and it’s unsustainable,” the country’s economy minister, Marcelo Ebrard, said on Tuesday, Bloomberg News reported. “We will present our arguments on Friday to exclude Mexico from this measure.”

The move received praise from at least one industry group: the American Iron and Steel Institute.

Kevin Dempsey, the group’s president, said the tariff hike “will help prevent new surges in imports that would injure American steel producers and their workers.”