Stocks fell across the world after U.S. President Donald Trump said his earlier threat of "fire and fury" against North Korea "maybe wasn't tough enough," with European markets opening down after heavy declines in Asia and the U.S.

The Kospi Composite Index closed down 1.7% in Seoul and the Hang Seng Index slid more than 2%. The South Korean won slid as much as 0.5% against the dollar. The FTSE 100 fell 1% by 4:19 a.m. ET.

Earlier, the S&P 500 closed 1.45% lower and the Nasdaq Composite dropped 2.1% Aug. 10.