"Cybersecurity represents a unique and evolving challenge to US national security planners and practitioners. Global interconnectedness facilitated by the internet has created unprecedented opportunities for international commerce and communication. The evolution of cyber technology provides many positive benefits, but significant security risks come along with it. The United States must be prepared to meet a range of cyber challenges such as cyber-crime, cyber-espionage, and cyber-sabotage. Cyberspace is a domain unlike any other. There are no physical boundaries in cyberspace; actions taken by a group or an individual on one continent can precipitate an immediate effect on a target located on the other side of the world. There are no physical walls, security fences or border checkpoints to prevent malicious cyber activity from crossing international borders. The cyber domain is a virtual domain that allows for anonymity in addition to the ease and low cost of operating within it. Cyberattacks may be perpetrated by states, non-state actors, or individuals and attribution of such attacks can be exceedingly difficult. Damage sustained by cyber-attacks is generally intangible, or non-physical, and yet such attacks can have disastrous effects. Both the public and private sectors are vulnerable to cyberattack."
United State Air Force Academy: http://www.usafa.edu/