'Russian troops' guarding Crimean government HQ
1 March 2014 Last updated at 12:44 GMT
Sergiy Aksyonov, the new pro-Moscow leader of Ukraine's autonomous Crimea region, has asked Russian President Vladimir Putin for help to ensure peace.
He was speaking at the first meeting of his cabinet, installed after the overthrow of President Viktor Yanukovych.
The BBC's Daniel Sandford has been to Crimea's local government offices in Simferopol.
He says "what appear to be Russian troops" are standing guard at the building.