WASHINGTON (Reuters) -U.S. President Donald Trump announced on Wednesday a 50% tariff on copper, saying on social media that it would be effective August 1 and that the decision was made after a national security assessment.

"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," Trump said in a post on Truth Social.

Trump signaled on Tuesday that he was imposing fresh tariffs on copper, sending U.S. Comex copper futures to record highs.