President Donald Trump's threats to impose high tariffs on countries make U.S. trading partners and investors nervous. But his sector tariffs could hurt consumers and businesses more in the long run.

US President Donald Trump’s plans to place hefty import tariffs on copper have already caused a spike in costs for American factories, with New York futures trading 25% higher than other global benchmarks on Tuesday.

U.S. President Donald Trump on Tuesday said he would impose a 50% tariff on imported copper and soon introduce long-threatened levies on semiconductors and pharmaceuticals, broadening his trade war that has rattled markets worldwide.