Even a week ago, the idea of a Russian military intervention in Ukraine seemed farfetched if not totally alarmist. The risks involved were just too enormous for President Vladimir Putin and for the country he has ruled for 14 years. But the arrival of Russian troops in Crimea over the weekend has shown that he is not averse to reckless adventures, even ones that offer little gain. In the coming days and weeks, 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. Here’s why:

At home, this intervention looks to be the one of the…