Global markets plunged Tuesday after President Donald Trump reignited fears of a U.S. trade war with the European Union, America’s largest trading partner.

Trump showed no signs of backing off his threat Saturday to hit seven E.U. countries and the United Kingdom with new tariffs unless they supported his push for American control of Greenland.

At a White House briefing Tuesday, Trump was asked how far he would be willing to go to secure control of Greenland, a semi-autonomous Danish territory. “You’ll find out,” he replied.

Monday, Trump had responded “no comment” to a question from NBC News about whether he would be willing to use force to seize the territory.

The S&P 500 ended Tuesday lower by around 2.1%, its worst day since…