This article seeks to analyze the frameworks and forms of cooperation between military and police forces in a contemporary world characterized by a growing militarization of the field of public security. The correlation between military and police has not only occurred in peace-building missions under the baton of multilateral organizations such as the UN and NATO, but also in the fight against organized crime, illegal trafficking, insurgency and terrorism that have intermingled, forcing governments to provide coordinated interagency responses, which has led to a blurring of the boundary between plain defense and pure citizen security. This proposal analyzes these two variants of police-military cooperation and coordination. Despite differences in ethos, culture, missions and firepower, the combined actions of both bodies have been essential to reestablish, first, the rule of law and institutional reconstruction and, second, to confront new threats to national security. However, little is known about combined military-police actions in Latin America against terrorism and drug trafficking. This project seeks to delve in detail into the latter aspect.