In 2007, the websites of the big government ministries, media outlets and banks in Estonia suddenly went offline. The information black-out lasted for three weeks. What was going on? The online arbiters of official reality in this former Soviet-dominated republic had become the victim of a Distributed Denial of Service (DDoS) attack by a group of political hacktivists. So many information requests were being sent to the servers of the targeted organisations, that they overloaded and effectively shut down. In a disaster, this kind of information short-circuit can be triggered by mass panic as much as by malicious sabotage. All of which leaves first responders with the potential hazard of being cut off from their command post, their sensors crippled and their intelligence compromised. For more on cyber-war in Estonia, see http://www.wired.com/politics/security/magazine/15-09/ff_estonia