This book provides an in-depth account of military operations against drug gangs and organizations in two of the biggest countries in Latin America: Brazil and Mexico. Recent studies on drug wars have detailed case studies on the war on drugs but do not focus on the role of the army in such policies. Publications that do drive attention to the military in such situations are usually from human rights organizations or the press and are therefore not scholarly works. There are therefore no recent academic books dealing with the role of the military in the fight against drugs in Latin America. This book aims to fill this gap. It also offers an empirical and theoretical examination of the issue of the role of the military (rather than the police) on national soil—the army being generally devoted to interventions abroad, and the police, to law enforcement on the national ground. The book is also the first work to look at high-level negotiations between military and civilian elites that define the conditions for the use of force during military operations. It provides a theoretically informed understanding of contemporary security politics in Brazil and Mexico.