1 Rational Terrorists and Optimal Network Structure

2 After the events of 9-11, US counterterrorism became more proactive in that the Patriot Act allowed the authorities far more freedom to directly attack terrorist network structures. We argue that rational terrorists will attempt to thwart such policies and restructure themselves to be less penetrable. We model the trade-off between security and intra-group communication faced by terrorists. The model is used to derive the anticipated changes in network structure and the consequent changes in the type, complexity and success rate of potential terrorist attacks.