Trump says 50% tariff on copper will begin Aug. 1

U.S. President Donald Trump said that the 50% tariff on copper imports, which he announced earlier on Tuesday, will begin on Aug. 1.

The decision was made after he received a national security assessment, Trump said in a post on Truth Social.

"I am announcing a 50% TARIFF on Copper, effective August 1, 2025, after receiving a robust NATIONAL SECURITY ASSESSMENT," Trump wrote.

"Copper is necessary for Semiconductors, Aircraft, Ships, Ammunition, Data Centers, Lithium-ion Batteries, Radar Systems, Missile Defense Systems, and even, Hypersonic Weapons, of which we are building many. Copper is the second most used material by the Department of Defense."

Adam Whiteley of BNY Investments said on CNBC's "Squawk Box" that Trump's latest announcement is indicative of the trade policy that he wants to protect.

"Copper is probably in a third category of tariffs, which is national security. So we've got negotiating tactics, we've got addressing trade imbalances, and then the copper, or indeed, any of the minerals, maybe semiconductors, maybe pharmaceuticals," Whiteley said.

Copper is the third-most-consumed metal, behind iron and aluminum. The U.S. imports nearly half of the copper it uses, most of which comes from Chile, according to data from the U.S. Geological Survey.Trump in late February ordered a probe into potential new tariffs on copper imports on national security grounds.

— CNBC's Kevin Breuninger contributed to this report.

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