When Trump paused his higher April 2 tariffs, he left in place a 10% charge on most trading partners. Separate levies on steel, aluminum and autos remain. And Trump has promised a range of new import taxes on copper, semiconductor chips, pharmaceutical drugs, lumber and aircraft parts — all of which could drive up the total effective tariff rate.

"If that is not the case, a tariff of at least 25% must be paid by Apple to the US."Adding uncertainty to his ultimatum, Trump later said the tariff wouldn't apply to just the iPhone but also to any smartphone made outside the US.

Stocks slumped on Friday after President Trump lobbed new tariff threats at the EU and Apple, reviving the trade anxiety that had gradually subsided over the past month.