Ukraine has told the UN that 16 thousand Russian troops have been deployed to the Crimea region.

While Russia has told the security council that Ukraine's deposed President Viktor Yanukovych asked Moscow to deploy the troops to his country.

Both Washington and the EU are now looking at a range of sanctions against Russia, over its threat to use force against Ukraine.

The US Ambassador to the UN, Samantha Power, says military action by Russia cannot be justified.