This thesis examines Ukraine's multi-vector foreign policy orientation and its causes. The dynamics of political evolution in Ukrainian domestic politics are also considered and it is argued that Ukraine's foreign and security policy can be characterised as subjective, pragmatic and evolutionary, but also marked to a large degree by continuity. Moreover, this project investigates the extent to which Ukraine's foreign policy is influenced by its geopolitical position between Russia and the West. It is suggested that a new East-West frontier is emerging between those states which have been invited to join key Western institutions such as the North Atlantic Treaty Organisation (NATO) and the European Union (EU) and those which have not. This thesis explains that the definition of what constitutes a modem frontier is in the midst of change; it is widening and narrowing, while undergoing erosion with respect to many issues and reinforcement with respect to others. The frontier, as such, resembles a 'third level' of analysis- it is neither the domestic nor the international arena, rather it is a place where crucial political developments unfold and where domestic and foreign politics converge. It is argued that Europe's frontier is differentiated by a lack of mechanisms in a rather structure-less geopolitical space through which authority is exercised. Although some regional structures have begun to emerge and develop a basis for exercising authority in various sectors such as energy and regional trade relations, the frontier is still under-organised. Furthermore, due to the processes of globalisation, transnationalism, and interdependence many regional frontiers in the world are softening and in some cases, even disappearing, as globalisation has tended to reverse the inclination to solidify borders. However, this thesis argues that in Europe the opposite is occurring; the frontier in Europe is not only widening, it also appears to be hardening.