The Standard & Poor's 500 index fell 20 points, or 0.8 percent, to 2,453 as of 10:09 a.m. Eastern time. The Dow Jones industrial average slid 69 points, or 0.3 percent, to 22,016.
The Nasdaq Composite dropped 49.53 points, or 0.78 per cent, to 6,320.93.
Investors opted for the perceived safety of US Treasuries, which pushed the yield on the 10-year note three basis points lower to 2.21%. The stock lost $142.20, to $1,906.80.
MARKETS OVERSEAS: Major indexes in Europe were headed lower.
"We've seen this play before, and it usually plays out where it just goes back to the status quo", Jacobsen said.
Small-company stocks fell more than the rest of the market Wednesday.
"Military solutions are now fully in place, locked and loaded, should North Korea act unwisely".
The remarks, following North Korea's earlier revelation of a plan to launch a salvo of ballistic missiles toward the U.S. Pacific territory of Guam, gave investors further incentive to take to the sidelines at least in stock markets.
Perrigo surged 16.08 percent after the drugmaker raised its full-year adjusted profit forecast. The stock fell $3.30 to $30.09.
The data comes amid tepid inflation that has remained below the Fed's 2 percent target, despite low unemployment.
In Europe, the pan-continental STOXX 600 index fell 0.9 per cent, with falls deepening after a auto rammed a group of soldiers in Paris, injuring six, in what officials said was a suspected terrorist attack. Shares of fellow department store J.C. Penney dropped 15% Friday after the company's second-quarter loss exceeded expectations. Wall Street was poised for a soft opening with S&P futures and Dow futures both down 0.2 percent. Rival Advanced Micro Devices was also down 2.6 percent. The Swiss currency was also on track for its biggest daily gain against the euro since the Swiss National Bank removed its cap on the currency in January 2015. Its shares slid $9.77, or 5.3 percent, to $174.02.
OIL: Benchmark U.S. crude lost 24 cents to $48.37 per barrel on the on the New York Mercantile Exchange while Brent crude, used to price worldwide oils, declined 20 cents to $51.70 per barrel in London. Brent crude, used to price global oils, gained 10 cents to $52.24 in London. Hong Kong's Hang Seng Index plunged by 2%, while South Korea's Kospi Index slumped by 1.7%.
Gold rose 0.6 per cent to $1,268 an ounce. The September copper contract was down two cents to US$2.91 a pound.
Energy stocks retreated 0.5 percent, despite higher oil prices.
Offsetting the declines was a 0.4 percent gain by the materials group, which includes gold producers.