The Small World of 9/11 and the Implications for Network Dismantlement Strategies

We retraced the development of the network of those who participated in the 9/11 attacks through four stages: 1998-99, December 2000, May 2001 and August 2001. We established that throughout its development, the network had the characteristics of a small world. The implications of this result pointed towards an easily detectable but difficult to dismantle network due to its large clusters. We then assessed the performances of traditional measures of network strength and node centrality. We found that although betweenness surpasses all other measures for all stages, we could improve its performance. The new measure, termed the Jenga index, proved to perform best through all stages.