This is an interesting question and this article in the Washington Post starts to answer this.
Currently, there are multilateral economic sanctions against Russia from a great deal of the Western powers. The article claims:
“From Russia’s perspective, the revealed preferences of goosing the Ukrainian conflict just before the G-7 summit suggests that the geopolitical benefits of destabilizing Ukraine outweigh the economic costs of continued sanctions.”
But what of the US, again this piece give some interesting thoughts:
So it appears that both Russia and the United States have a vested interest in continued conflict. Russia wants to weaken Ukraine, not be seen as knuckling under to sanctions, and wait for fissures to appear in the Western alliance. But the United States sees the calculus of conflict a bit differently. U.S. officials think that continued conflict will help to perpetuate the sanctions and the number of dead Russian soldiers in Ukraine. This elevates geopolitical risk and makes it harder for Putin to suppress the domestic costs of his Ukraine adventure.
I still have to ask: to what end? I am not sure I really see the reason on Putin’s end or on Obama’s.