| Abstract |
Objectives: The current research examines how the security/efficiency tradeoff shapes the evolution of dynamic terrorist networks by focusing on the structural properties of these collectives. First, some argue that terrorist groups develop as chain-like, decentralized structures in an attempt to maximize security. Others maintain that terrorist networks form patterns of redundant ties and organize around a few highly connected individuals, or central hubs, to increase operational efficiency. We investigate these structural tradeoffs and consider whether tendencies toward efficiency versus security vary at different phases of a terrorist networks formation. Methods: Using a variety of descriptive network measures and Separable Temporal Exponential Random Graph Models (STERGMs), we consider patterns of tie formation across eleven multi-wave terrorism networks from the John Jay & ARTIS Transnational Terrorism database. Our dataset includes networks from prominent attacks and bombings that occurred in the last three decades (e.g., the 2002 Bali Bombings), where nodes represent individual terrorists and ties represent social relationships. Results: Despite the need for illicit networks to promote security, our results suggest that there is a tendency for attack-based terrorist networks to become increasingly well-connected and efficient as they prepare for a violent incident. We also find evidence that highly central nodes develop even more ties in the years directly preceding an attack, signifying that the evolution of terrorist networks tends to be structured around a few key actors. Conclusions: Our findings have the potential to inform counterterrorism efforts by suggesting which actors in the network make the most influential targets for law enforcement. We discuss how these strategies should vary as extremist networks evolve over time. |