Most South-east Asian stock markets closed lower too, as investors flocked instead to traditional safe-havens such as gold, the Japanese yen, and the bond market.
On commodities markets, oil advanced with USA crude nearing $50 a barrel after figures from industry group the American Petroleum Institute showed a sharp decrease in stockpiles, a clear indication of an easing supply glut.
Those moves left the Stoxx Europe 600 down by 0.7% to 379.84, with only the utilities sector, considered defensive, notching a small gain at the close. Trump's comments came after a Washington Post report that North Korea has built a miniaturised nuclear warhead.
Six of the S&P 500 sectors ended higher. Ten-year USA yields dropped 4 basis points to 2.242 percent and German equivalents fell 3 bps to 0.43 percent, a six-week low. The yield on the 10-year Treasury note held steady at 2.26 percent.
The index's losses mirrored global markets, which fell after incendiary words between the United States and North Korea.
News late Tuesday that North Korea was reviewing plans for an attack on USA military assets on the island of Guam came just hours after President Trump had warned that continued threats would be met "with fire and fury like the world has never seen".
Options traders gear up for Snap's second earnings report as a public company. Orders fell 4.7 percent from the previous quarter in April-June, suggesting demand is weaker than expected, though economists say such measures are not overly important. The stock fell $3.30 to $30.09.
Dow e-minis were down 35 points, or 0.16 percent, with 37,467 contracts changing hands at 8:40 a.m. ET (1240 GMT). The stock fell 85 cents to $12.76. It added 39 cents to $49.56 a barrel overnight.
Health care equipment and services company Henry Schein declined amid a broader slide by health care stocks.
The European dip followed similar trading in Asia, where equities were back in the red, snuffing out a nascent recovery as tensions over North Korea lingered for a second day. Brent crude, used to price worldwide oils, added 4 cents to $52.74. Equity benchmarks in Germany and France on Wednesday fell by more than 1% each, marking their worst sessions since July 21.
Unit labor costs had been expected to climb by 1.2% compared to the 2.2% jump that had been reported for the previous quarter. Silver gained 14 cents to $16.39 an ounce.
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