But the Russian economy outside of oil and gas sucks. I think Putin also wants to be sure Russia does not see the kind of "Orange Revolution" that got rid of Yanukovich the first time. Unfortunately for the Ukraine, their leadership has been totally corrupt and their economy has been horrible.
No strategic planning or diplomatic strategy by EU and USA for the last many years has given Putin freedom to do whatever he wants. Economic isolation of Russia at this point is not going to happen because EU does not want to make the sacrifice it would require. Plus they know USA is a totally unreliable ally that has spent itself into a black hole.
So Kerry is going to Kiev in a couple days and I suppose he will find some pretext to announce "peace in our time". Lucky for us Obama told Vlad that he would have more flexibility after his second election. Now we can all see what he meant.