This article tries to shed light on why gas relations between the EU and Russia, which were previously stable, have deteriorated since the introduction of institutional changes in the two regions. After identifying the areas of divergence in the context of European gas market liberalization, we then attempt to examine them in the context of the differing approaches to structuring this sector. The model of vertically unbundled network industries promoted by the EU is no longer the one that Russia intends to implement in its gas sector, despite the big changes taking place in its domestic market. All this is happening in a context where the economic stakes are very high. For the EU and its gas companies, access to Russia's hydrocarbon resources is a key question. For Gazprom, the question is whether or not it can define strategies that are flexible enough to adapt to the changing conditions in the European gas market. (C) 2012 Elsevier Ltd. All rights reserved.