WASHINGTON (AP) — The White House is warning Russia against intervening in eastern Ukraine and threatening further sanctions.

White House spokesman Jay Carney says there’s strong evidence that some pro-Russian protesters who have taken over government buildings in eastern Ukraine were paid, and not local residents. He says escalation in Ukraine is the result of increased Russian pressure.

Advertisement - Continue Reading Below

Carney says if Russia moves into eastern Ukraine either overtly or covertly, it would be a very serious escalation.

He’s calling on Russian President Vladimir Putin to cease efforts to destabilize the area. He says Russia must pull back its troops from the border.

Pro-Russian separatists in the eastern Ukrainian city of Donetsk have also proclaimed the region independent. The chain of events has raised concerns about a repeat of Russia’s annexation of Crimea.