Welcome to our coverage of the unfolding crisis in Ukraine as Russia's president asks his parliament to send in troops on the grounds of protecting Russian lives. With the biggest crisis in the former Soviet Union since the 2008 war in Georgia taking a dangerous new turn, stay with us for live news updates, expert analysis and colour from our correspondents in the field and your comments.
Vladimir Putin made his request to send troops in a brief statement released by his office. Read the full translation.
Russian soldiers are already on the territory of Crimea as part of the country's Black Sea Fleet. These soldiers were spotted outside a Ukrainian border post in the Crimean town of Balaclava.
Russia's upper house of parliament has approved Mr Putin's request to use Russian forces in Ukraine - less than two hours after the request was made.
Unlike most legislation in Russia, the use of armed forces abroad only requires the approval of the upper house, with no need for a preliminary okay from the lower house (the State Duma), AFP news agency notes.
The situation on the Ukrainian-Russian border is stable, Ukraine's border service has told Interfax news agency. It is quoted as saying: "Border control has been stepped up at the border checkpoints to look for extremists and extremist groups."
J Bentley in Loule, Portugal
emails: Someone need tell the Ukrainians beguiled by EU promises that the EU countries who fell for the same promises are now in desperate trouble with millions out of work and starving as is now happening in Portugal where I live