Britain could move to expel Russia from the Council of Europe in response to any further incursions in eastern Ukraine, the Attorney General has said.
Speaking in the House of Commons, Dominic Grieve said "nothing is ruled out at all" when asked whether Russia could be thrown out of the organisation of 47 member states that have signed up to the European Court of Human Rights.
Mr Grieve said Russia had been "tearing up the rulebook" in its annexation of Crimea.
The Prime Minister had vowed to look at a "range of sanctions and responses" to further Russian moves in the region, he added.
An unusually frank Nato Secretary General issued an unequivocal warning on the course of events should Russia attack Latvia or Estonia.
The West responds with sanctions and closer political ties with Ukraine as Russia's President seals the annexing of Crimea to much fanfare.
Supporters of the controversial fracking industry believe shale gas could be America's most potent weapon in the stand-off with Russia.