Turmoil in Moscow was in focus after the head of the Wagner mercenary group, Yevgeny Prigozhin, launched but then abandoned a mutiny that threatened to undermine Kremlin chief Vladimir Putin.

About 10 minutes into trading, the Dow Jones Industrial Average was up slightly at 33,7441.21.

The broad-based S&P 500 added 0.1 percent at 4,352.64, while the tech-rich Nasdaq Composite Index advanced 0.2 percent to 13,513.74.

Putin did not personally address the crisis, but made a video speech to a youth forum and praised industry for overcoming "severe external challenges."

"In brief, Prigozhin and his mercenaries will not be marching on Moscow, yet his actions have infused a bit more geopolitical uncertainty into the mix," said Briefing.com analyst Patrick O'Hare.

This week's calendar in the United States includes durable goods orders for May, data on personal income and prices for the same month, plus a reading on consumer confidence.

The reports come as Wall Street weighs the likelihood of additional Federal Reserve interest rates hikes after the central bank paused its increases earlier this month.