The Standard & Poor's 500 index fell 5.99 points, or 0.2 percent, to 2,474.92.
The Nasdaq Composite was down 37.30 points, or 0.59 percent, at 6,315.03.
North Korea claimed "only absolute force" can work on someone as "bereft of reason" as Trump and detailed plans to fire a salvo of missiles into waters around the U.S. Pacific territory of Guam.
Nevsun Resources Ltd offset some of the material group's gains, plunging 18.4 percent to C$2.685 after the company reported disappointing quarterly results. It was last up 0.0 percent at 1.1329 per euro EURCHF= .
Meanwhile, gold stocks bucked the downtrend, driving the NYSE Arca Gold Bugs Index up by 1.3%.
Safe haven Treasuries climbed late Tuesday and overnight Wednesday as tensions between the US and North Korea escalated to frightening threats.
Charter Communications rose 2.9 percent on news Altice is exploring a bid for the cable giant.
The thirty-year bond auction drew a high yield of 2.818 percent and a bid-to-cover ratio of 2.32, while the ten previous thirty-year bond auctions had an average bid-to-cover ratio of 2.29. European stocks (http://www.marketwatch.com/story/european-stocks-fall-as-caution-over-geopolitical-tensions-linger-2017-08-10) were also in the red. Gold and bond prices were headed higher.
"The president also has the power in the Constitution to defend the USA and take all necessary measures if we are threatened, I struggle to understand how there would be a threat so grave that the preemptive response from this administration would be a nuclear bomb". The Dow shed 0.2 percent.
Hong Kong was down more than one per cent. Shanghai and Seoul were also down. Lockheed Martin, Raytheon, General Dynamics and Northrop Grumman all rose, with the Dow Jones US defense index up 1.48 percent at 409.58.
ENERGY: Benchmark U.S. crude lost 23 cents to $48.94 per barrel in electronic trading on the New York Mercantile Exchange.
In commodities, crude oil stretched gains after rising overnight on data pointing to declining US inventories.
The Swiss franc reversed a two-week losing streak, rising rose 1.12 per cent versus the greenback at 0.96 per dollar.
CURRENCY: The dollar declined to 109.79 yen from Tuesday's 110.34 yen. Gold hit a two-month high of $1,278 an ounce amid the nervousness.
The market indexes wavered between small gains and losses for much of the morning, then veered lower by afternoon.
Markets were also lower in Europe and Asia.