http://www.rand.org/publications/MR/MR1339/

Current instability in Colombia derives from the interaction and resulting synergies stemming from two distinct tendencies: the development of an underground criminal drug economy and the growth of armed challenges to the state's authority. The first source of instability is reflected in the increasingly pervasive influence of drug networks and their infiltration of key societal institutions; the second is the growth of guerrilla armies as well as the development of organized violence perpetrated by illegal self-defense forces, also known as paramilitaries. The actions of drug traffickers, guerrillas, and paramilitaries have exacerbated deeper problems in Colombian society: the central government's loss of authority, economic deterioration, and social disintegration.