An indicator of German investor confidence dropped to its lowest level in 20 months. Investors worried that the Ukraine crisis will start dragging down the German economy, Europe's largest. The continent is much more exposed to Russia than the U.S. Europe also gets most of its natural gas from Russia.
The Ukraine situation has dragged the German stock market down more than 8 percent from its early July peak.
"The Ukraine-Russia situation may be at a standstill politically, but it is weighing on the German economy and, more broadly, the eurozone," said Sean Lynch, a managing director at Wells Fargo Private Bank.
It has been a quiet week for investors overall, with little economic data or company earnings to work through. Absent hard data to pull the market higher, the current trend for the market is down, Lynch said.
Fears of a Russian invasion of Ukraine have faded in recent days, but worries about conflicts around the globe are likely to keep investors on edge in the coming weeks.
A convoy of more than 260 Russian trucks, reportedly packed with supplies, moved toward Russia's border with Ukraine on Tuesday, but Kiev said the goods would only be allowed to cross if they were inspected by the International Red Cross. Ukraine is fearful that Russia could use the move as a cover for sending troops into the separatist-held territory.
Investors are also watching political machinations and violence unfold in oil-rich Iraq. On Tuesday, that nation's embattled prime minister, Nouri al-Maliki, tried to stay in power as Iraqi politicians and the international community rallied behind a political competitor.
The Dow Jones industrial average lost 9.44 points, or 0.1 percent, to 16,560.54. The Standard & Poor's 500 index fell 3.17 points, or 0.2 percent, to 1,933.75 and the Nasdaq composite fell 12.08 points, or 0.3 percent, to 4,389.25.
Energy stocks in the S&P 500 fell 0.7 percent, the most of the 10 sectors in the index. Kinder Morgan declined nearly 2 percent after rising 9 percent the day before on news it would combine several companies under its control. Anadarko Petroleum and Diamond Offshore Drilling fell more than 2 percent.
Energy stocks have declined noticeably in the last month, due largely to falling oil and natural gas prices. Brent crude, which is traded in the U.K. and is considered a broader gauge of the international oil market, is trading at a nine-month low. U.S. crude is trading at a seven-month low.
The price of U.S. crude oil slipped 71 cents to $97.37 a barrel Tuesday. That followed three days of increases over concerns about the reliability of Iraqi oil production.
There were other signs that investors were in a "risk-off" mode. The Russell 2000 index, which is made up primarily of smaller and riskier companies, fell 0.8 percent, much more than the rest of the market.
In individual stocks, Kate Spade plunged $9.87, or 25 percent, to $29 after executives for the handbag company warned that sales growth could slow this year and profit margins were being hit. The comments came after Kate Spade reported a better-than-expected quarterly profit.
The yield on the 10-year Treasury note rose to 2.45 percent. In metals trading, gold rose 10 cents to $1,310.60 an ounce, silver fell 19 cents to $19.51 an ounce and copper fell two cents to $3.15 a pound.