The Nikkei futures contract in Chicago was trading at 56,735, while its counterpart in Osaka was last at 57,000.

Trump renewed threat to target Iran's civilian infrastructure if a peace deal is not reached in less than 24 hours, while signaling Iranian leadership is negotiating in earnest.

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."