Earlier, U.S. stocks swung sharply during regular trading as uncertainty about the war with Iran increased after Trump had threatened that a “whole civilization will die tonight."

In an expletive-filled social media post, Trump also vowed to bring "Hell" to the country after the U.S. forces had rescued an American airman shot down in Iran last week.

Earlier, U.S. stocks swung sharply during regular trading as uncertainty about the war with Iran increased after Trump had threatened that a “whole civilization will die tonight."