Putin will have to decide how far he is prepared to take this intervention and how much he is prepared to suffer for it. It is already clear, however, that he cannot emerge as the winner of this conflict, at least not when the damage is weighed against the gains. It will at best be a Pyrrhic victory, and at worst an utter catastrophe.
http://news.yahoo.com/4-reasons-putin-already-losing-ukraine-211452971.html
