"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.

A 50 percent tax on European imports would hit the continent hard, hurt the U.S. economy and slow growth globally.