S. are solidly realist, and have responded in line with that, the EU has always been a quintessentially liberal organization. Tang (2008) notes that liberalism falls into a non-realist point-of-view that holds cooperation in high regard, and argues that states cannot assume the worst of each other -- that the world is not a zero-sum competition. This offers an explanation for EU inaction -- it feels that Russia does not intend to pursue significant annexations beyond this point, and that cooperation is ideal because it will defuse the conflict and avoid the worst-case scenario (The Nation, 2014). The realist view blames EU dependence on Russia's gas for its inaction, but the liberalist view points out that the EU is predisposed to cooperation, especially since open conflict with Russia would destroy Europe a lot more than it would harm North America -- it is easier for the Americans to be realist because they have less at stake.
The constructivist point-of-view on international relations is notes that the ideological conflict -- the acute differences between Western and Russian societies -- are a considerable factor in this conflict. This view is especially powerful in examining the Ukrainian internal narrative, of a country split. On one side is a group with leanings towards democracy and liberty, and driven by a need to establish a coherent sense of ethnic identity (where there was none prior to the late 1800s) and on the other side is a group with no real inclination towards democracy and liberty, that mistrusts the West, and that has a strong sense of ethnic identity. The constructivist understands this conflict as being between these two opposing views. In light of the constructivist understanding, a split of the Ukraine seems to be inevitable -- the two constituent groups are unlikely to ever get along, and if anything the social schism between the two has only become larger over time.
The constructivist view understands that Ukraine will probably be split, with the ethnic Russian parts absorbed into the Motherland. The realists -- Russia and the U.S. -- have probably already accepted this, knowing full well that open conflict serves nobody's interests. The U.S. has to recognize that Russia taking over territory occupied by ethnic Russians is not actually expanding its sphere of influence, even if it appears to be doing just that. The EU might not see this as a great solution, but it would likely welcome a compromise outcome that saw a smaller, pro-Western Ukraine join the EU and NATO, which for the U.S. would have to be seen as a win (albeit a smaller one than the best-case scenario). The ongoing situation in Ukraine is certainly not one of anarchy, despite appearances. The different actors are essentially behaving in very predictable ways according to their established perspectives on international relations. The result of this is that the developments in Ukraine are fairly predictable when evaluate on a macro view, and that the country will likely be split -- all sides probably already understand this and all that's left is to see how it plays out.
Jakes, Lara & Burns, Robert. (2014). Kerry: Russia accelerating Ukraine crisis. Yahoo News. Retrieved April 30, 2014 from http://news.yahoo.com/kerry-russia-accelerating-ukraine-crisis-203708665 -- politics.html
Baczynska, Gabriela, Polityuk, Pavel & Kasolowsky, Raissa. (2014). Timeline: Ukraine crisis and Russia's standoff with the West. Reuters. Retrieved April 30, 2014 from http://www.reuters.com/article/2014/04/27/us-ukraine-crisis-events-timeline-idUSBREA3Q0CC20140427
Tang, Shiping (2008) Risk aversion. International Studies Review. Vol. 10 (3) Sept. 2008 451-471.
Fedesenko, Vasily. (2014). Ukraine separatists seize second provincial capital. Reuters. Retrieved April 30, 2014 from http://www.reuters.com/article/2014/04/29/us-ukraine-crisis-idUSBREA3S0F720140429
Korab-Karpowicz, Julian (2013). Political realism in international relations. Stanford Encyclopedia of Philosophy. Retrieved April 30, 2014 from http://plato.stanford.edu/entries/realism-international-relations/
AP. (2014). Ukraine crisis: Kharkiv mayor Hannady Kernes shot in the back. CBC News. Retrieved April 30, 2014 from http://www.cbc.ca/news/world/ukraine-crisis-kharkiv-mayor-hennady-kernes-shot-in-the-back-1.2623922
The Nation. (2014). Time for realism and common sense on Ukraine. The Nation. Retrieved April 30, 2014 from http://www.thenation.com/article/178655/time-realism-and-common-sense-ukraine