The CBOE Volatility Index, better known as the VIX and the most widely followed barometer of expected near-term stock market volatility, rose the most in about 12 weeks.
"If the US and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so", the editorial's authors said.
"The markets in general are very on edge and they're very leery about risk", Mariann Montagne, a portfolio manager at Gradient Investments, told Bloomberg.
Nasdaq 100 e-minis were down 1 points, or 0.02 percent, on volume of 49,062 contracts. The stock fell another 2 cents, or 0.4%, to 5.12 Friday.
"It's awesome when you consider the headlines just how calm the equity markets are, how they've taken things in their stride", said Ryan Detrick, senior market strategist at LPL Financial in Charlotte, North Carolina.
Politics lifted US defence stocks. Lockheed Martin, Raytheon, General Dynamics and Northrop Grumman all rose and the Dow Jones US defence index was up 1.6 per cent after hitting a record high.
"It gives them nearly a mental excuse to sell".
Until this week, the equity market had managed to shake off negative news, including previous saber-rattling over North Korea and failures in Washington to pass high-profile bills, such as repealing and replacing Obamacare.
"Although we certainly can get a 5 to 7 percent correction, we don't think it's the start of a significant bear market", Peterson noted.
In Europe, Britain's FTSE100 was down over one percent, Germany's DAX traded 0.5 percent lower, while the French CAC40 index was 0.62 percent in the red, as of 9:00am GMT.
The Dow slid as declines in Apple and Goldman Sachs, down 2.3% and 1.7% respectively, outweighed gains in McDonald's and Coca-Cola, up 1.4% and 0.5% respectively. South Korea's KOSPI fell 1.8 percent to almost a three-month low.
Retailers were all under pressure after Macy's and Kohl's each reported lower second-quarter sales, reviving worries about consumer discretionary stocks.
Shares of Snap were off about 13 percent premarket following the social media company's earnings that came below estimates and a slew of price target cuts.
The latest United States economic data cemented expectations that inflation will remain subdued amid a robust labour market.
The Labor Department said its consumer price index inched up by 0.1 percent in July after coming in unchanged in June. "The pot is on the stove boiling but no inflation steam is coming out".