The study found that the ABDP contributed to the displacement of coca cultivation from Peru to Colombia, an increase in Peruvian and Bolivian cocaine production, and a proliferation of trafficking routes. This occurred because law enforcement pressure was applied selectively, traffickers cleverly avoided interdiction, and South American security forces were relatively weak. Numerous contingent conditions contributed to displacement as well. An example of contingent conditions were the status of law enforcement operations in Colombia and a general restructuring of the Colombian drug industry, which reduced the importance of the drug smuggling air bridge between Peru and Colombia. This contributed to an increase in Colombian coca cultivation and influenced the operations of the Bolivian and Peruvian drug industries. Such contingent conditions pose significant problems for the development of a theory of what causes displacement and should lead to the abandonment of the oversimplified "balloon" metaphor. This metaphor reasons that when a balloon partially filled with air (the cocaine supply) is squeezed (selective interdiction), the air is not reduced but simply moves to another area of the balloon. This study drew on official publications, press reports, secondary literature, fieldwork in South America, and publications of activist-research institutions that have established themselves as reliable information sources. 173 notes