Futures point to a lower open as Street reacts to Middle East tensions

U.S. stock index futures pointed to a lower open on Tuesday as traders reacted to escalating tensions in the Middle East and awaited the testimony of former FBI Director, James Comey.

Dow futures slipped 46 points, while S&P and Nasdaq futures dropped 6 points and 8.5 points, respectively.

Tuesday will see Job Openings and Labor Turnover Survey (JOLTS) data for April released at approximately 10 a.m. ET. The U.S. quarterly financial report for the first three months of the year is also due at around the same time.

On the earnings front, HD Supply Holdings and Michaels Cos are both scheduled to report before the bell. Ambarella, Dave & Buster's and Duluth are all due to report after the market close.

In Europe, the pan-European Stoxx-600 index was around 0.53 percent lower on Tuesday morning. In Asia, the Shanghai Composite in China closed 0.35 percent higher, while the Nikkei in Japan closed 0.95 percent lower.

In oil markets, Brent crude traded at around $49.31 a barrel on Tuesday, down 0.32 percent, while U.S. crude was around $47.25 a barrel, down 0.3 percent.

Oil prices gyrated around low levels in choppy trading on Tuesday as investors feared multiple Middle Eastern countries cutting diplomatic ties with Qatar could undermine OPEC efforts to curtail a supply overhang.