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A miner stands among copper production at El Teniente mine, the world’s largest underground copper mine in Machali, near Rancagua, Chile, in April.RAUL BRAVO/AFP/Getty Images

U.S. President Donald Trump on Wednesday signed a proclamation ordering 50-per-cent tariffs on certain copper imports, citing national security, the White House said.

The proclamation imposes a 50-per-cent tariff on semi-finished copper products and copper-intensive derivative products as of Aug. 1, according to a fact sheet released by the White House.

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The tariffs will exclude copper scrap and copper input materials such as copper ores, concentrates, mattes, cathodes, and anodes, the statement said.

The measure came after a U.S. investigation under Section 232, which Trump ordered in February.

Along with tariffs, the order calls for steps to support the domestic copper industry, including requiring 25 per cent of high-quality scrap produced in the U.S. to also be sold within the country.