During a bitter cold snap, countries from France to Turkey are faced with growing shortages of natural gas. Ukraine says Russia's Gazprom monopoly has cut off all shipments to Europe. Russia insists it's Ukraine that has shut down pipelines that cross its territory. The European Commission calls it "unacceptable" for Europe to be a hostage to the dispute. Marshall Goldman, senior scholar in Russian studies at Harvard, is author of Petrostate: Putin, Power and the New Russia.