The United States said Monday it is sending all of its diplomats in Ukraine to Poland out of security fears, hours after President Vladimir Putin ordered Russian troops into two rebel-backed regions in the country, NDTV reported.

Earlier, the Kremlin leader recognized the independence of two rebel-held areas of the Donetsk and Lugansk areas of Ukraine. He then instructed his defense ministry to assume a "peacekeeping" role in the separatist regions.

"Today the Department of State is again taking action for the safety and security of U.S. citizens, including our personnel. For security reasons, Department of State personnel currently in Lviv will spend the night in Poland," Secretary of State Antony Blinken said in a statement.

"We strongly reiterate our recommendation to US citizens to depart Ukraine immediately. The security situation in Ukraine continues to be unpredictable throughout the country and may deteriorate with little notice," he added.

The move comes just over a week after the US relocated its embassy in Kyiv to Lviv, citing the "dramatic acceleration" in the build-up of Russia's forces on the border.