Russian President Vladimir Putin says there is no need yet to send Russian troops into Ukraine, but he has not ruled out doing so.
Russia reserves the right to use “all means” to protect citizens in Ukraine, he told a news conference.
Russian and Ukrainian troops in Crimea are involved in a tense stand-off.
Mr Putin called the toppling of President Viktor Yanukovych in the capital Kiev an “anti-constitutional coup and armed seizure of power”.
He said “militants” had plunged the country into “chaos”. He also said Ukrainian “nationalists” and “anti-Semites” were roaming the streets of Kiev and other cities.
If Russian-speaking people in eastern Ukraine asked for Russia’s help then Moscow would respond, he said.
In Crimea pro-Russian armed men and civilians are surrounding Ukrainian military bases – not Russian soldiers, he said.
Mr Yanukovych had agreed to all that the opposition wanted, Mr Putin said.
He insisted that Mr Yanukovych was still the legitimate president.
There were only three legal means to remove a president, he said: death, personal resignation or impeachment.
Mr Yanukovych fled to Russia, and Mr Putin told the news conference: “I don’t think he has a political future.”
Russia had helped him for “humanitarian” reasons, he said, “otherwise he’d just have been killed”.