Information security is more than just a fact of life-it is a guarantor of life. Government, the military, the commercial sector and the public are so dependent on cyberspace that any interruption or degradation can be chaotic or even catastrophic. And, scarcely a day goes by without the public learning of either some new intrusion into key government systems or a discovered threat to personal information. SIGNAL Magazine's July 2009 issue examines the challenges of achieving information security from the burgeoning menace to potential solutions-and their own ramifications. Leading off is "Threats Imperil the Entire U.S. Infostructure," an article on the information security challenges daunting the Free World. These run the gamut among profiteers, saboteurs and spies, and their activities have increased in both scope and sophistication over the past 18 months. Private-sector experts offer their views on what may be necessary for government, industry and the public to regain a degree of security for the increasingly important infosphere. At the heart of the battle for cyberspace is the U.S. Defense Department, and "Defense to Turn Network Security Inside Out" describes the department's roadmap for information assurance. Robert Lentz, deputy assistant secretary of defense for cyber, identity and information assurance and chief information assurance officer for the department, gives a detailed description of the department's new information assurance strategy. Those who forget the past are condemned to repeat it, and Estonia is one nation that does not want a repetition of the cyber attacks that crippled it a couple of years ago. In Cyber Attacks Reveal Lessons, Business Editor Henry S. Kenyon describes what happened then through the eyes of an Estonian official who was part of the recovery effort-and who has helped draft response plans for the next cyberassault. Closer to home, the U.S. Air Force has incorporated information operations into its everyday mission set. News Editor Rita Boland reports in "Flying Military Branch Maneuvers in Cyberspace" how the atmosphere is not the only realm in which the Air Force prepares for warfighting operations-both defensive and offensive. These concerns raise the question of just who is responsible for cyberspace security. Contributing Editor Col. Alan D. Campen, USAF (Ret.), addresses that issue-with some interesting conclusions-in "Who's Watching Your Six in Cyberspace?"