US STOCKS-Wall St falls in choppy trading on Russia concern
* Aetna, other health insurers fall after Goldman note
* S&P 500 tests support as it dips below 100-day average
* Jobless claims fall unexpectedly in latest week
* Indexes off: Dow 0.3 pct, S&P 0.4 pct, Nasdaq 0.3 pct (Recasts, updates prices, changes comment, adds Aetna, Harman)
By Rodrigo Campos
NEW YORK, Aug 7 (Reuters) - U.S. stocks fell in choppy trading on Thursday as a sanctions confrontation between Russia and the West kept traders eager to cash any gains.
The S&P 500 had risen as much as 0.45 percent on the back of some strong earnings and a surprise tick lower in applications for unemployment insurance, before selling off to trade below its 100-day moving average for a second consecutive session. It has closed below that level just four times this year, the last one in mid April.
Markets kept an eye on eastern Europe as Moscow imposed a ban on imports of many Western foods, retaliating against sanctions imposed for its support of rebels in eastern Ukraine and the annexation of Crimea. Russia will ban various imports from the United States, the European Union, Australia, Canada and Norway in a measure that isolates its consumers from world trade to a degree unseen since Soviet days.
"The Russian situation has gone from bad to worse," said Brian Jacobsen, chief portfolio strategist at Wells Fargo Funds Management in Menomonee Falls, Wisconsin, adding that "imposing an import restriction on agricultural products will likely lead to rapid inflation." Continuación...