Turchinov said Russia was waging a war against Ukraine by sowing disorder in the east of the country, but he offered not to prosecute any militants who gave up their weapons by Monday morning.
Accordingly, Russia's foreign ministry said that such an announcement by the authorities in Kiev is a "criminal order."
The ministry said the West should bring its allies in Ukraine's government under control. "It is now the West's responsibility to prevent civil war in Ukraine," the foreign ministry said in a statement.
The statement also said that Russia would put an urgent discussion of the situation in eastern Ukraine on the agenda of the United Nations Security Council.
NATO described the appearance in eastern Ukraine of men with specialized Russian weapons and identical uniforms without insignia - as previously worn by Moscow's troops when they seized Crimea - as a "grave development."
Power said on ABC's "This Week" the latest events in Ukraine bore "the telltale signs of Moscow's involvement."
"I think we've seen that the sanctions can bite and if actions like the kind we've seen over the last few days continue, you're going to see a ramping up of those sanctions," Power said.