U.S. President Donald Trump attends an event to sign an executive order authorizing the construction of an access road to the Ambler mining district in Alaska, at the White House, in Washington, D.C., U.S., October 6, 2025. REUTERS/Kent Nishimura

WASHINGTON (Reuters) -U.S. President Donald Trump on Monday said he had signed an executive order directing his administration to permit an access road to the Ambler mining district in Alaska to unlock domestic supplies of copper and other minerals.

The White House also announced a $35.6 million investment in Canada's Trilogy Metals, one of the region's possible developers. The investment makes the U.S. government a 10% shareholder in the company and includes warrants to purchase an additional 7.5% stake.

U.S.-listed shares of Trilogy more than doubled in after-hours trade to $4.72.

“This partnership represents a strong vote of confidence in the Ambler Mining District and is a major step forward for domestic mineral development that’s fundamental to America’s security and economy,” said Kaleb Froehlich, managing director of Ambler Metals, a joint venture between Trilogy and Australia's South32 Limited.

Trump's order reverses the Biden administration's rejection of a 211-mile (340-km) road intended to enable mine development in the north central Alaskan region. Biden's Interior Department in 2024 had cited risks to caribou and fish populations that dozens of native communities rely on for subsistence.

"This is something that should have been long operating and making billions of dollars for our country and supplying a lot of energy and minerals and everything else that we are talking about," Trump said at a signing event in the Oval Office.

The Alaska state agency that proposed the project appealed the Biden administration decision.

Environmental group Sierra Club said development in the region would harm pristine landscapes that support tribes and wildlife.

"Communities along the proposed route of the road have consistently made their voices clear in opposing this damaging project," Athan Manuel, director of Sierra Club's lands protection program, said in a statement. "This order ignores those voices in favor of corporate polluters."

(Reporting by Steve Holland in Washington and Nichola Groom in Los Angeles; Editing by Franklin Paul and Lincoln Feast.)