Social Network Analysis as an Approach to Combat Terrorism: Past, Present, and Future Research (2006)

IntroductionThe greatest security threat facing the United States is not from formal states, but from terrorist organizations that attack informally, using terror at any time and place, with the goal of undermining confidence in U.S. institutions and the American way of life. No longer a structured battle that can be fought with military power, the war against terrorism will be won with superior knowledge.Due to the changing nature of homeland security issues, a new type of intelligence is needed by homeland security: social network analysis (SNA). basis of social network analysis (also known as network science or network sociology) is that individual nodes (which, depending on the type of network, can be people, events, etc.) are connected by complex yet understandable relationships that form networks. 1 These networks are ubiquitous, with an underlying order and simple laws. Networks form the structural basis of many natural events, organizations, and social processes.Terrorist organizations are well-suited to study using social network analysis, as they consist of networks of individuals that span countries, continents, and economic status, and form around specific ideology. Terrorist organizations are different from hierarchical, state-sponsored appointments in characteristics such as leadership and organizational structure. Social network analysis can provide important information on the unique characteristics of terrorist organizations, ranging from issues of network recruitment, network evolution, and the diffusion of radical ideas. Specifically, social network analysis can be used to understand terrorist networks, inform U.S. homeland security policy, and form the basis of a more effective counter-measure to net war.Social Network AnalysisThe origin of contemporary social network analysis can be traced back to the work of Stanley Milgram. 2 In his famous 1967 experiment, Milgram conducted a test to understand how people are connected to others by asking random people to forward a package to any of their acquaintances who they thought might be able to reach the specific target individual. 3 In his research, Milgram found that most people were connected by acquaintances. This research led to the famous phrase six degrees of separation, which is still widely used in popular culture.Another important step in the development of social network analysis was the work of Mark Granovetter on network structures. In his widely-cited 1973 article The Strength of Weak Ties, Granovetter argues that - your relationships with acquaintances - are more important than strong - your relationships with family and close friends - when trying to find employment. 4 Granovetter's article and subsequent research extended this argument by positing that more disperse, non-redundant, open networks have greater access to information and power than smaller, denser, and more interconnected networks because they supply more diversity of knowledge and information.D.J. Watts' small world hypothesis builds upon both Milgram's six degrees of separation concept and Granovetter's argument by stating that most networks in the natural and man-made world are highly yet far-reaching. 5 These networks have a clustered center, where most nodes are neighbors, tightly interconnected. In addition, each has weak ties that can connect it to any node in the network in a few short connections. For example, if a node represents a person, a person's friendship network is generally tightly connected, with common friends, similar backgrounds, and overlaps. However, despite this clustered inner core, as shown with Milgram's six degrees of separation, a person can reach a stranger in the world through only a few small steps/connections. Watts' small world argument has been extended by numerous researchers to help understand the structure and behavior of various networks, including the spread of AIDS, the collapse of financial markets, and the spread of information. …