This policy brief focuses on the interplay of external actors in the South Caucasus, i.e. the EU, NATO and Russia, looking specifically at how political and security relations have been shaped. Three main issues are highlighted: firstly, that the South Caucasus is a heterogeneous area and that the concept of being a region in its own right is underdeveloped; secondly, that despite the enlarged involvement of international players in the area, the South Caucasian countries retain agency and are not mere agents of foreign role-players; and, thirdly, that the area is characterised by processes of competition and collaboration that do not necessarily meet common agendas, despite shared interests regarding regional stability. The paths of the three South Caucasian republics has been different, with Armenia being dependent on Russia, Azerbaijan pursuing a policy of independence regarding external players, and Georgia assuming a pro-Western, anti-Russian position. The lack of diplomatic relations between Armenia and Azerbaijan due to the Nagorno-Karabakh conflict, EU involvement in crisis management in the wake of Georgia’s 2008 war with Russia, a diminished NATO presence and increased Russian assertiveness in the area are central elements to understanding ongoing policies and practices. This complex framework suggests the need to address challenges and opportunities in the South Caucasus in terms of the complexity of the actors and factors at play.