It looks like a major boost in Russia’s bid to safeguard its European gas market. Ankara is said to have agreed “in principle” to let Russia’s South Stream pipeline pass through Turkish territorial waters.If such a deal is signed on Prime Minister Vladimir Putin’s visit to Turkey’s capital today, it would help Russia undermine the rival EU-backed Nabucco pipeline. Turkey is no stranger to that project either. Last month, it hosted the signing of a key transit deal with EU countries for Nabucco. The EU-flagship pipeline is designed to counter Russia’s strong influence on European energy supplies. Currently, Moscow supplies a quarter of Europe’s natural gas. And Russia is reluctant to give that up, hence its South Stream initiative, developed with Italian energy giant Eni. With a key deal on that project set to be signed today, the pipeline war is far from over.