Since taking office in January, Trump has announced sweeping duties that could hit both allies and adversaries while also targeting sectors like steel and aluminium – moves that may reshape global supply chains.

The imposition of tariffs or other barriers on copper could fuel trade tensions with Chile, the biggest US supplier accounting for about 35% of imports, as well as Canada.

Trump on Tuesday signed an executive order tasking his commerce secretary with studying copper imports in order to end unfair trade.

“Tariffs will help build back our American copper industry, and strengthen our national defence,” Trump said on his Truth Social platform shortly after the signing.

“Our great American copper industry has been decimated by global actors attacking our domestic production,” said commerce secretary Howard Lutnick in a statement.

“To build back our copper industry, I will investigate the imposition of possible tariffs,” Lutnick added.

The world’s biggest economy has been increasingly dependent on copper imports to meet domestic consumption needs.

Copper is used in military hardware like aircraft, but growing demand for the metal is also linked to a boom in artificial intelligence and data centres.

Lutnick said Tuesday: “It’s time for copper to come home.”

US officials did not commit to a deadline for the investigation or potential tariff rate.

The probe will take place under Section 232 of the Trade Expansion Act, the same tool used to justify steep tariff hikes on steel and aluminum imports previously.

Such probes focus on the harm that certain imports – in this case copper and derivatives – could have on US national security.

These investigations can take months and do not necessarily result in action, though US officials said Lutnick would move quickly, “in Trump time.”

With copper, considering both mining and refinery production, the US produces just a fraction of what countries like Chile and China do, a White House official said.

While the US sits on ample copper reserves, it lacks smelting and refining capacity, the official added.

On Tuesday, Peter Navarro, Trump’s senior counsellor for trade and manufacturing, accused China of using a model of industrial overcapacity and dumping among means “to gain control of the world’s copper markets.”

Besides tariffs aimed at specific sectors, Trump has also announced and paused sharp tariff hikes on major trading partners Canada and Mexico.