U.S. copper futures slump nearly 4% to three-week lows on Thursday after President Trump unveiled his plan for an array of reciprocal tariffs, ratcheting up a trade war that threatens to hurt the global economy and demand for raw materials.

The tariffs are viewed as more aggressive than expected, with a 10% duty on all exports to the U.S. and even higher rates on ~60 nations, including 34% on China and 20% on the European Union; commodities including energy, steel and aluminum were exempted for now, although tariffs on copper are expected within weeks.

Front-month Comex copper (HG1:COM) for May delivery -3.9% to $4.844/bbl, and shares of top copper producers trade broadly lower, including Freeport-McMoRan (NYSE:FCX) -7.1%, Southern Copper (SCCO) -4.6%, Teck Resources (TECK) -6.7%, Hudbay Minerals (HBM) -5.6%, Ero Copper (ERO) -5.4%.

Diversified global miners show milder declines: BHP (BHP) -2.1%, Rio TInto (RIO) -1.1%, Vale (VALE) -0.5%.

ETFs: (CPER), (COPX), (OTC:JJCTF)

Domestic copper prices had increased YTD beyond those in the rest of the world as traders and manufacturers raced to bring metal into the U.S. ahead of tariffs, but today's decline suggests that traders now expect weaker demand for copper.