The current south american scenario in defense and security matters is characterized by its dynamic nature and its degree of complexity. At present, the Armed Forces continue to fulfill their main traditional roles associated with defense against external aggressions originating in other states. At the same time, threats to the security of the state and its citizens from non-state actors who operate within a transnational dynamics and use of violence according to asymmetric criteria are at the top of the hemispheric agenda. The article focuses on the ten latin nations in South America and defines whether over the last few years Armed Forces have been used -and in what manner- against two specific transnational threats, i.e., terrorism and organized crime. Objectives pursued will be to highlight the heterogeneity of our continent when it comes to the use of the military against these threats, as well as to evaluate whether there are prospects for effectively channeling military cooperation in this area through regional multilateral institutions.