Stocks are on track for a flat open as investors continue to weigh last week's U.S. missile strike in Syria and weekend reports that the U.S. is sending several strike-group ships near the Korean peninsula; S&P, Dow and Nasdaq all flat.
European bourses are lower, with France's CAC -0.5%, Germany's DAX -0.2% and U.K.'s FTSE -0.1%; in Asia, Japan's Nikkei closed +0.7% but China's Shanghai Composite finished -0.5%.
In corporate news, Straight Path Communications +151% after AT&T agreed to buy the company for $95.63/share, and Knight Transportation and Swift Transportation agreed to an all-stock merger, sending their respective shares +8.5% and +18.9%.
WTI crude oil +1.1% at $52.82/bbl on the shutdown of Libya's largest oil field and continued Middle East concerns following last week's Syria strike.
Still ahead: Janet Yellen is due to speak at the Univ. of Michigan at 4:10 p.m. ET.