Updated – 5:36 a.m. ET
Dozens of armed men seized the regional government and parliament buildings in Crimea where protesters for and against Ukraine's new provisional government clashed, a local Tatar leader told Russian news agency Interfax on Thursday.
"I have been told that the buildings of parliament and the council of ministers have been occupied by armed men in uniforms that do not bear any recognizable insignia," Refat Chubarov said on Facebook.
"They have not yet made any demands," he said. Images from the scene showed a Russian flag raised over the parliament building.
Thousands of ethnic Russians protested near the building in Simferopol on Wednesday to appeal for the Kremlin's intervention to protect Ukraine from its opposition leaders. "Crimea is Russian!" some screamed, as fights broke out between demonstrators supporting and those opposed to Ukraine's new provisional government in Kiev.
Russian President Vladimir Putin ordered thousands of troops to areas near the Ukranian border as part of a massive military exercise, which is expected to last until March 3, according to reports.
Defense Secretary Chuck Hagel and other top-level U.S. defense leaders were notified of the operation before Russian troops moved out early Wednesday, Defense Department spokesman Lt. Col. Robert Firman told BuzzFeed.
Moscow has ordered improved security measures at Russia's Black Sea Fleet headquarters, located on the Crimean peninsula in Ukraine, as part of the ongoing military exercises, Russian Defense Minister Sergei Shoigu announced Wednesday.