The purpose of this chapter is to discuss the impact of the latest European Union (EU) enlargement on actorness in an international environment. The question of EU actorness is of crucial importance for our understanding – and indeed the existence – of a triangular relationship between the USA, Russia and the EU. Can a Union of 25 member states think and act strategically, and will it be attributed strategic capacity by the two other actors making up the triangle? We begin looking for answers by considering eastward enlargement through the prism of new security threats, the changed signiﬁcance of geography and geopolitics, the assets brought in by new member states, along with the dual role/identity of the Union as both a global network player and a more traditional actor. We conclude by elucidating implications of this somewhat intricate equation, as well as of the interplay between the EU and the other two players, in the form of four scenarios.