The idea behind this monograph arose from a long-standing interest in European energy security, which became acute after the winter 2006 dispute between Russia and Ukraine over gas supplies. It seemed then, as it still does today, that energy security will become one of the defining security issues of the twenty-first century. Much attention has rightly been focused on climate, food and water security. However, tackling climate change and dealing with the potential security fallout (for instance, conflict over resources and forced mass migration) has always been closely associated with the need for an effective and co-ordinated global energy security strategy. In this context, ensuring energy security and preventing disruption and conflict presupposes a co-ordinated effort by governments to avoid disaster. This paper argues that 'energy diplomacy', and the effort to ensure security of energy supply, should be a top political priority, both of governments and the diplomatic corps which support them. Nowhere is this more true than for the European Union, which is becoming increasingly dependent on imported sources of energy, particularly oil and gas.