Keith Darden has really good piece in Foreign Affairs arguing that

inattention to Ukraine’s internal demons reflects a dangerous misreading of current events; the struggle between Russia and the West has been a catalyst, but not a cause. The protagonists in this conflict are subnational regions. The EU association process, and especially the protests, repression, and revolution that followed, activated very deep and long-standing divisions between them. Unless Kiev deals with its regions and installs a more legitimate, decentralized government, Ukraine will not be won by the East or the West. It will be torn apart. 

Since the problem is an internal Ukrainian problem (and remains so, despite Russia’s annexation of Crimea, the presence of tens of thousands of Russian troops on the country’s borders, and the seizure of city administrations throughout eastern Ukraine by pro-Russian groups), the solution will also be Ukrainian. The country might not be able to fix its centuries-old divides, but it must finally craft institutions to accommodate them. 

Later on in the piece he documents the extent to which regional rivalries threaten to wreck the country — and provide excuses for Russian intervention — unless they are addressed creatively by the regime in Kiev.