This book explores the extraordinary difficulties a nation-state’s law enforcement and military face in attempting to prevent cyber-attacks. In the wake of recent assaults including the denial of service attack on Estonia in 2007 and the widespread use of the Zeus Trojan Horse software, Susan W. Brenner explores how traditional categories and procedures inherent in law enforcement and military agencies can obstruct efforts to respond to cyberthreats. Brenner argues that the use of a territorially-based system of sovereignty to combat cyberthreats is ineffective, as cyberspace erodes the import of territory. This problem is compounded by the nature of cybercrime as a continually evolving phenomenon driven by rapid and complex technological change.