I think Putin [and the Russian oligarchs] may pay a heavy price for the move into Ukraine. But if he is willing to pay that price, there is little or nothing either we or the EU can do about it. Huffing and puffing and calling on Obama to be "tough" is pointless. We can inflict economic punishment on Russia, we can [though it will be interesting to see whether we do] freeze the billions that the Russian oligarchs have parked in Western banks, we can cancel the G8 meeting and even exclude Russia from it -- we can probably not stop them from selling their oil, the world market for oil being what it is. But it would be madness to launch a military strike against the one country in the world that could actually retaliate devastatingly against us. My guess is that Obama and his advisers know all this. Indeed, I would imagine that everyone but some silly neo-con hawks and Republicans facing primary challenges know this. [Lindsey Graham is despicable in so many different ways that it is difficult to get worked up about his foolishness in this particular case.]
Fifty odd years ago, when I taught at the University of Chicago, I became friendly with Hans Morgenthau, a grand old European emigre who had a cold-eyed view of Central European realpolitik. He helped me to look past the moralizing and posturing to the objective facts on the ground of power and national interest, which had shaped the basic story of Europe for four centuries.
It remains to be seen whether Putin has sufficient control over his oligarchs to force them to accept whatever economic punishment the EU decides to inflict. Who knows? He may be overplaying his hand, although I would not want to bet on it.