How to make Russia stick to ceasefire

Russia's President Vladimir Putin attends The State and Civil Society forum in Moscow on January 15, 2015

(CNN)The argument against sanctions is that, although they might raise the costs for Russia, Putin has shown that he does not respond to higher costs in a rational, calculating manner. But if that's the case, then military aid for Ukraine wouldn't work, either. No one believes that Kiev can prevail in a military contest with Moscow. A recent think-tank report by former U.S. government officials urging military aid acknowledges that the package would merely raise the costs for the Kremlin in order to force it to negotiate. In other words, the consensus among experts is that the only possible strategy is to raise the costs for Russia. The disagreement is really about what kinds of costs Putin finds onerous.

Military aid to Ukraine would stoke the fires of Russian nationalism, let Putin wrap himself in military colors and defend his "fellow Russians" in an arena in which he will be able to ensure that Moscow prevails. For a regime that waged two bitter and costly wars in Chechnya, a region far less central to the Russian imagination than Ukraine, the loss of some men and money in a military operation is not likely to be much of a deterrent.