Wall Street on edge as Tillerson heads to Moscow to discuss Syria

U.S. stock index futures pointed to a marginally lower open on Tuesday as Secretary of State Rex Tillerson arrives in Moscow amid tensions over Syria.

Traditional safe-havens caught a bid early on Tuesday as Gold futures for June delivery rose 0.65 percent to $1,262 per ounce, while the benchmark 10-year note yield slipped to 2.341 percent.

Tillerson has been mandated by foreign ministers from the Group of Seven (G-7) major industrialized nations to put pressure on Russia to break ties with Syrian President Bashar Assad.

Tillerson said Tuesday the U.S. will stand up against anyone who commits crimes against humanity.

"We rededicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world," Tillerson told reporters while commemorating a German Nazi massacre committed in Italy in 1944.

On the data front, the NFIB small business optimism index slipped to 104.7 in March from 105.3 in February. The JOLTS (job openings and labor turnover) data are also due at 10 am ET.

In Europe, the pan-European Stoxx-600 index was around 0.2 percent higher on Tuesday morning. In Asia, the Shanghai Composite in China closed 0.58 percent higher, while the Nikkei in Japan closed 0.27 percent lower.

In oil markets, Brent crude traded at around $55.82 a barrel on Tuesday, down 0.3 percent, while U.S. crude was around $52.96 a barrel, down 0.2 percent. Prices traded higher earlier, both buoyed somewhat by concerns over supply limitations following continued tensions in the Middle East.

Elsewhere, Neel Kashkari, president of the Federal Reserve Bank of Minneapolis, is due to speak Tuesday.

—Reuters contributed to this report.