NEW YORK: Wall Street stocks retreated early Tuesday as Russian President Vladimir Putin's latest escalation of the Ukraine conflict stoked volatility in markets.

Putin on Monday announced recognition of independence for two separatist enclaves in Ukraine -- and moved troops into the areas saying Russia's military would be responsible for what he called "peacekeeping."

Western governments condemned the move, with the German government halting certification of a key natural gas pipeline and Washington signaling imminent plans for "severe" sanctions.

About 15 minutes into the first trading session of the week after a long holiday weekend, the Dow Jones Industrial Average was down 0.8 percent at 33,813.83.

The broad-based S&P 500 dropped 0.4 percent to 4,330.98, while the tech-rich Nasdaq Composite Index slid 0.3 percent to 13,503.62.

Gyrations in the Treasury and oil markets on the latest developments in Ukraine suggest investors "still aren't convinced a worst-case scenario will come to fruition," said Briefing.com analyst Patrick O'Hare.

US stocks lower amid Ukraine uncertainty

"The continuum from worst to best, however, includes a lot of diplomatic potholes at the moment that could make for a bumpy ride."

Besides Ukraine, investors are watching data releases this week on consumer confidence and personal consumption for clues on key upcoming Federal Reserve decisions. The Fed has signaled it will "liftoff" from zero interest rates with the first rate hike announced March 16.

Among companies releasing earnings, Home Depot shares slumped 4.8 percent even after reporting better-than-expected results and raising its dividend by 15 percent.