Imports of certain copper products into the US face a 50% tariff from Aug. 1 as President Donald Trump seeks to revive the domestic supply chain and make the country less reliant on foreign sources of this critical material.

The president stopped short of putting a 50 percent tariff on refined copper, as he had threatened earlier this year. The market reaction was swift anyway and prices tumbled.

In a flurry of trade news on Wednesday, Trump imposed new rates on copper imports and ended the de minimis exemption.