The critical foreign policy and security challenges which the European Union faces in the 1990s are the result of the tense co-existence between a highly institutionalized West and disintegrating regions in its periphery. Given the traditions of European rivalries in the historical Balkans, the Yugoslav conflict presented the emergent European defence and security policies with a particularly demanding test. This paper is a brief and tentative examination of the difficulties encountered by the EU in its pacifying efforts in the Yugoslav crisis and of the prospects for future crisis prevention and crisis management. A number of conditions have allowed national foreign policies to take precedence over the pursuit of coherent EU policies, and these conditions are unlikely to change significantly in the foreseeable future. The EU's role in preventing and regulating conflict in its periphery will depend (a) on the institutionalization of mechanisms which will prevent or restrain the "renationalization" of European foreign policies, and (b) on the outcomes of internal EU debates about the relations between deepening and widening.
The absence of manifest conflict in international relations depends largely on the existence and strength of institutional arrangements mitigating the most stressful aspects of interstate interaction. The functioning of relatively stable interstate systems over long periods of time testifies to the role of norms and organizations institutionalizing international relations.1 The most severe conflict situations develop in periods of transition and uncertainty, when highly institutionalized systems dissolve in junctures involving the redefinition of roles by the major players, and before new institutionalized equilibria have been reached. Conflict in that interregnum helps determine subsequent arrangements, although resilient elements of the previous institutional design are also influential in shaping outcomes.
It is certainly not surprising that the collapse of the bipolar certainties would lead to at least the potential for intensified regional conflicts, as the Cold War bloc rivalries receded. The European security system currently finds itself in a period of transition, which appears to leave open a number of different future possibilities. Aspects of the uncertainty which characterizes a period of transition have been the coexistence of a highly institutionalized West and a disintegrating East; the relative instability accruing from traits such as the revival of nationalism; and the emerging global debates about the role of the United Nations (UN) and the composition of its Security Council. Regional conflicts have fueled debates about the role, legitimacy and limits of UN "humanitarian intervention" in particular (for an analysis see Wheeler, 1993, pp. 133-157). Such debates have been associated with a certain relativization of the principle of nonintervention in the internal affairs of states, a principle enshrined in the UN Charter. The weakening of the principle of non-intervention can be supported from a liberal theoretical standpoint by pointing to possible links between a state's authoritarian features at home and aggressive policy abroad; liberal theorists of international relations from Kant onwards have insisted that democracy is a prerequisite of international peace. Irrespective of one's theoretical viewpoint, the fact that non-intervention becomes relativized as an international norm is, in itself, an indication of uncertainty. Although non-intervention is anchored in the traditional conception of statehood which originates in the Peace of Westphalia, its potence in postWorld War II international relations helped create a bridge between the sovereignty-oriented structure of international relations and the contemporary international society which is characterized by dense interactions and close cooperation. As Cassese argues, non-intervention "currently …