Putin's options on Ukraine - in 60 seconds
18 March 2014 Last updated at 14:34 GMT
Russian President Vladimir Putin has signed a treaty to accept the "Republic of Crimea" into the Russian Federation, after its people voted to break away from Ukraine and join Russia.
The EU and US have declared Sunday's referendum illegal and announced travel bans and asset freezes against Russian and Ukrainian officials.
BBC News assesses the Russian leader's possible next moves.
Video produced by Michael Hirst