It appears that Russia has moved troops into the Crimea. This video shows Russian attack helicopters moving into Crimea ahead of 6000 troops to (to paraphrase the Russian media) protect Russian language speakers in the region. And it also appears that neo-Nazi groups are patrolling the streets in Kyiv. Strange bedfellows and all. The UN has asked Russia to explain its actions while the United States is calling on Russia to withdraw.
From a purely power politics perspective it is quite difficult to see what resources that the UN, the EU, or the US have to confront Russia in the Black Sea. A deal with Russia will have to be made but it is difficult to see the typology of the framework needed to de-escalate tension in the region outside of the issues with the Ukraine itself. I think a fair amount of pressure can be applied through both the EU and North American banking system with threats of confiscation of the offshore wealth of the Russian elites, but that would require a type of cooperation unseen in a while.
An interesting historical analysis at al Arabiya outlines the relationship between Russia and Turkey regarding the Crimea over the last several centuries. A treaty signed in 1793 holds that Crimea was never to be independent and, if so, would return to Turkish rule. More on the Treaty of Küçük Kaynarca here.
And here is a transcript of the leaked comments by the US ambassador on the overthrow of the pro-Russian leader. I put this link up because this forms a crucial piece of the puzzle when interpreting recent actions in Kyiv by the opposition parties. This provocation as a deliberate “new Cold War” thesis is provocative, to say the least.
Another point that it also interesting is the potential for this action by Russia as a precedent for other states “protecting language minorities” in, say, the Far North East.