05:51 AM EDT, 06/02/2025 (MT Newswires) -- US President Donald Trump threatened Friday to raise steel tariffs to 50% from a previous import duty of 25%, effective June 4.

"Our steel and aluminum industries are coming back like never before," he said in a post on his Truth Social account. "This will be yet another BIG jolt of great news for our wonderful steel and aluminum workers."

Shares of US steel and aluminum makers rose in Monday's premarket activity. Cleveland-Cliffs ( CLF ) was up more than 26%, Commercial Metals ( CMC ) gained more than 14% and Steel Dynamics ( STLD ) rose more than 13%.

US trading partners condemned the proposed move and warned of countermeasures.

The European Commission said Saturday that Europe was preparing to retaliate.

"This decision adds further uncertainty to the global economy and increases costs for consumers and businesses on both sides of the Atlantic," Reuters reported, citing a European Commission spokesperson.

Canada's Chamber of Commerce said the tariffs harmed North America's economic stability.

"Unwinding the efficient, competitive and reliable cross-border supply chains like we have in steel and aluminum comes at a great cost to both countries," Reuters cited Candace Laing, president of the chamber, as saying.

Australia's Trade Minister Don Farrell called it "unjustified and not the act of a friend," Reuters reported.