ENThe main aim of this study is to map changing energy relations in the Baltic Sea region (BSR) and to explore how the regional debate on energy security and energy policy has evolved and been translated into political action in the aftermath of two key watershed events – the 2004 EU enlargement that has changed the political and institutional / regulatory landscape of the region, and the outbreak of the armed conflict in Ukraine that has put the issue of energy security – and security in more general terms – very high on the European political agenda. It should be noted that both events should be seen in a longerterm perspective. The wish to join the EU had been gradually changing trade relations and regulatory norms of Central and Eastern European candidates (this group includes the Baltic States), while the accession itself was an important factor placing energy security issues on the EU agenda. Also, supply of energy resources from Russia has been an object of political tensions between the customer or transit countries in Central and Eastern Europe for more than a decade before Russia’s aggression against Ukraine in 2014, exerting important influence on energy policies of those EU member states which continued to purchase most of their energy resources from Russia, Baltic countries in particular. The latter factor explains why the energy security has been one of the most important European policy priorities of those countries since their accession to the EU. This study has a clear geographical focus and examines the framework conditions for energy relations and energy policies of 8 EU member states (Finland, Sweden, Denmark, Germany, Poland, Lithuania, Latvia, and Estonia), of one European Economic Area (EEA) member (Norway) and of the main external energy supplier of energy to Europe and at the same time a source of strategic concern, Russia.This group of countries – EU member states and a member of the EEA – is referred to in this study as a sub-region or the BSR to differentiate it from the regional integration within the framework of the whole EU (and the EU and the EEA). In order to understand how framework conditions in these countries have changed over time, we will take two snapshot pictures of energy situation in the region and map how the regional energy landscape has changed between 2004 – the year of the big bang enlargement – and 2014, the year of the definite end of ‘the end of history’ in the region, marked by Russian actions in Ukraine. Data used in this study stem from various sources, but to secure data consistency the two main sources used are the IEA annual data from 2004 (published in 2006) and 2012 (the last available set of data published in 2014), and the Eurostat that provides the most important data on energy situation in the EU and in member states. These data will be supplemented when necessary with data from other sources. The main focus of the first part of the study is on how the regional distribution of energy resources and energy policies of various actors involved in the regional energy game have contributed to increasing or decreasing the level of energy security in the whole region and in particular countries. The second part focuses on how various actors have addressed energy security concerns by taking various types of policy measures. In other words, the first part discusses in detail the actual changes in the patterns of trade and the character of interdependencies which characterise the dependent variable – energy security, while the second part of the study discusses the independent variable – regional and sub-regional cooperation which can account for the changes in the regulatory environment and infrastructural connections, which can increase energy security in the BSR. [From the Introduction]