This paper reviews the definition and the measurement of energy security based on an eclectic reading of the most recent literature. Energy security, economic competitiveness and environmental sustainability form an energy strategic trilemma. This trilemma is part of the most recent European strategy to build a European energy Union. This energy union is discussed in relation to the role the non-European Mediterranean countries can play in meeting their own strategic objectives, but at the same time contributing to the European Union's energy strategy. The paper concludes that this energy strategy is possible only if it is embedded in an overall strategy of economic, political, social and environmental development. 1