What are the causes and consequences of the Russia-Ukraine conflict?
It seems pretty clear the causes of the conflict between Russia and Ukraine consist of a combination of ethnolinguistic divisions and security concerns, with some small historical factors thrown into the mix. I'm a big fan of maps as a means of understanding issues. Below is a map that I feel represents the ethnolinguistic situation fairly well:
Unsurprisingly, the areas annexed by Russia -- particularly Crimea -- are those areas with a Russian ethnic majority or significant minority and that are Russian-speaking. I wrote last week about the extent to which Putin's foreign policy has been irrendentist at least with regard to the protection, if not annexation, of Russians living outside Russia's borders.
Another map lays out why security concerns caused the conflict:
This map of the Rada election results in 2014 shows People's Front (pro-EU) voters in the Ukrainian ethnolinguistic areas and the opposition in the Russian areas. Therefore, for Russia, concerns about accession to the EU and further separation of Ukraine from Russia at the very least provided a pretense for intervention. Finally, it bears noting that the USSR had bestowed Crimea on Ukraine only in the 1950s, so an historical argument could be made that, in the case of the peninsula, a legitimate claim cwas being made by Russia.
In terms of the consequences, the most important one, I think, is the extent to which it has brought Putin and Russia into further conflict with the EU and United States. Hawks in the U.S. had already been gunning for Putin over his intervention in Georgia, but the Obama administration had sought a "Russian reset," at least during Obama's first term. However, the Ukrainian conflict turned the relationship overwhelmingly negative, giving rise to Russian-U.S. conflict the full extent of which we have yet to see.