Russian parliament approves troop deployment in Ukraine
Russia's upper house of parliament has approved President Vladimir Putin's request for Russian forces to be used in Ukraine.
He had asked that Russian forces be used "until the normalisation of the political situation in the country".
Russia's Black Sea Fleet is based in the Ukrainian region of Crimea, where many ethnic Russians live.
Ukraine's acting President Olexander Turchynov said he had put the army on full alert but urged people to remain calm.
Daniel Sandford reports.