The European Union (eu) has played a central role in mediating the conflict between Georgia and Russia in August 2008. But the eu encounters difficulties and proves to be unable to define a set of strategies that gives it the role it would like to play in the different conflict resolution process in Abkhazia, South Ossetiya and Nagorno-Karabakh. This article intends to analyse the relative failure of the eu in this domain. It examines the logics particular to this supranational organization which could explain why the eu’s involvement in the South Caucasus’ conflict resolution could be considered to be a secondary one: the enp’s uncertainties and ambiguities; competitions between eu’s State-members, between the latter and the European institutions, or within institutions.