Two mainstream theories of international relations, Neo-liberalism and Neo-realism, have different perspectives on what are the incentives and limits for cooperation? Neo-liberalism argues that states tend to cooperate when they see the opportunity to maximize their absolute gains from cooperation. Whereas, for the Neo-realist school, state concerns about the relative gains of others limit cooperation. Using the great power rivalry for control of natural gas pipelines in the Caspian as a case study, we try to explain why the energy cooperation failed between the US and Russia in the west of...