The Yale Budget Lab noted that the letters sent Monday would hike the effective tariff rate on U.S. consumers to the highest since 1934.

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.

The EU is aiming for a July 9 deal, which would include a 10 percent baseline tariff. Trump has threatened to impose 50 percent tariffs if no deal is reached.

WASHINGTON—President Trump reignited his global trade war Monday, renewing his threat to hit partners with punishing tariffs even as he announced a three-week extension to negotiate deals. Trump signed an executive order extending the date when his so-called reciprocal tariffs would take effect,