Western nations have called on Russia to ease tensions in Crimea region in Ukraine.
The warning comes after armed men seized the local parliament and raised the Russian flag.
According to the BBC, Russia also scrambled fighter jets along its borders as part of military exercises it announced a day earlier.
Moscow said it was willing to work with the West on averting a crisis, but warned foreign powers against taking decisions on behalf of Ukrainians.
Meanwhile, the ousted Ukrainian president is reported to be in Russia.
Viktor Yanukovych plans to hold a news conference in the southern Russian city of Rostov-on-Don on Friday, a Russian news agency reported.