US President Barack Obama is ready to impose sanctions on Moscow over its thinly disguised takeover of Crimea.
In a phone call between the US leader and Russian President Vladimir Putin the two men are said to have disagreed over the legitimacy of the Moscow-backed secession referendum.
Both Washington and European foreign ministers meeting today in Brussels are likely to decide to slap targeted sanctions on several Russian officials, assets and bank accounts.
While the West has said it will not recognise the referendum result, military action has been ruled out.
All sides have stressed the necessity to stabilise the situation in Ukraine and a need to deploy international monitors in the crisis torn country.