The book examines Brazil's role in regional security and defense policy cooperation, emphasizing collaboration with major South American players like Argentina and Chile. The defense cooperation, rooted in the 1990s, has evolved to address transnational threats such as organized crime and terrorism. It poses critical questions about Brazil's contributions as a regional leader in developing a security community in Southern Latin America and the current stage of this cooperation. To address these, the author employs a three-layered research design that analyzes factors influencing Brazilian security policy across state and society, intraregional relations, and the international system. This conceptual framework enhances theoretical literature by identifying factors that either promote or hinder cooperative Brazilian security policy, thereby affecting the security community's development. The findings reveal Brazil's pivotal role in fostering a security community in Southern Latin America, with its cooperative stance positively impacting regional security collaboration, particularly through its partnership with Argentina. The stable relationship between Brasilia and Buenos Aires serves as a "strategic center of gravitation" for other South American nations. Chile also plays a unique role in defense cooperation. Within Mercosur, smaller states engage in collective efforts to combat non-military threats, although the principle of n
