Ukraine's government accused Moscow of working behind the scenes with pro-Russian separatists who have moved to claim independence in three different cities, while the U.S. warned Russia to back off.

Speaking at a Cabinet meeting on Monday, Ukraine Prime Minister Arseniy Yatsenyuk accused Moscow of being behind the recent move by separatists who are trying to claim independence from the country, reports USA Today. "Russia's scenario is division and destruction of Ukraine."

Yatsenyuk added, "The plan [is] for foreign troops to cross the border and attack the country. We won't let it happen."

Pro-Russian separatists took over several public buildings in three different eastern Ukrainian cities, Kharkiv, Luhansk and Donetsk. Those in Luhansk were able to storm a security services building by throwing eggs, stones and even a firebomb and smoke grenade.

While separatists are claiming freedom from Ukraine, citizens in those cities are frustrated that police aren't doing enough to get them out, while an activist involved in Donetsk uploaded a video asking that Russia provide peacekeeping troops.

The U.S. is backing Ukraine and agreeing that it looks like the separatists are being quietly helped by Moscow, according to Reuters. White House spokesman Jay Carney said, "There is strong evidence suggesting some of these demonstrators were paid and were not local residents."

He added a warning directed towards Moscow while speaking with reporters, "If Russia moves into eastern Ukraine either overtly or covertly this would be a very serious escalation."

Carney said that if Russia continues to try to "destabilize Ukraine," the U.S. will look into additional sanctions, a move that hasn't bothered Russia much yet.