The twin threats, delivered via social media, roiled global markets after weeks of de-escalation had provided some reprieve.

Stock markets declined after the president’s early-morning threats of 25 percent import taxes on iPhones and 50 percent on goods from Europe.

WASHINGTON ― President Donald Trump reignited trade tensions ahead of the Memorial Day weekend with back-to-back social media posts targeting Apple and the European Union, sending global markets into another round of turmoil after weeks of de-escalation provided some reprieve.