The war crippling the world's biggest oil producer By: CNBC.com News April 24, 2015 at 10:44 AM EDT As tensions in the Ukraine escalate, European sanctions are squeezing Russia's energy sector. Production is flat, and oil deliveries are down. Read More >> Related Stocks: Exxon Mobil Novatek Jt Stk Oao Gazprom ADR Totalenergies Se ADR