Overlapping regional security institutions in South America: The case of OAS and UNASUR

The Union of South American Nations (UNASUR) has positioned itself as a regional security organization aimed at reducing the influence of the Organization of American States (OAS) in South America. At the same time, the OAS paradoxically serves as a model for UNASUR because of its operational capacity and its legitimacy as a regional organization. This article analyzes the seemingly contradictory tendencies of replication and dissociation that UNASUR exhibits towards the OAS in terms of security conceptions and practices. In the first part of the paper, we will draw on recent debates on international regime complexity to develop a framework to study institutional overlap. The second part analyzes to what extent and in which respects UNASUR, and particularly its Defense Council, overlaps with the OAS in terms of security conceptions and practices, while the third part examines the causes of the emergence of a “competitor” for the OAS in South America.