Since the 11 September attacks, police and intelligence officials have been forced to add a new dimension to their planning: groups of highly skilled “cyber-terrorists”.
"The first cyber-terrorism attack will most likely not be somebody targeting a company. What we will see is a blended, or multi-prong attack," said Richard Starnes, director of incident response for British telecom firm Cable & Wireless and an adviser to Scotland Yard's Computer Crime Unit.
A potential scenario might be this: A truck carrying explosives races towards the main entrance of a city centre rail station at rush hour, just as a computer whiz hacks into the emergency response telephone network.
There is a huge blast. With the communications system knocked out, police and rescue units are paralysed. Emergency teams lose precious minutes attending to the scene and the toll of dead and injured climbs.
Internet was extensively used in
run-up to September 11 attacks
This type of chain of events was, until recently, spoken about in hypothetical terms. Now, police forces and intelligence agencies around the world say it's not a matter of if, but when.
Security officials have many names for a scenario in which computer attacks are combined with a real world armed plot - "Cyber Terrorism," "Blended Digital Threats," even "Digital Armageddon".
With more of the world's critical infrastructure - from power grids to air traffic control networks to emergency response hotlines - linked to computer networks, the risk of a hacking intrusion has become all the more tangible.
And armed groups, already adept users of the latest technologies, are honing their hacking skills to maximise bloodshed, experts said.
"We will see a force multiplier effect where you hit a chemical factory, for instance, at the same time you lodge a digital attack. That way, they can ratchet up the body count by delaying the response time for essential emergency services," Starnes said.
"September 11 was a modern-day plot, one that could have only happened in 2001"
adviser,Computer Crime Unit,
Scotland Yard, UK
A wave of cyber crime and damaging e-mail viruses has made Internet security an urgent topic at the highest levels of government and law enforcement.
Last week, industry and national security officials met in both California and Germany to brainstorm on the matter. This week, leaders from over 200 nations will meet at a United Nations IT conference in Geneva to discuss boosting network
In the September 11 attacks some of the hijackers coordinating their movements by mobile phone, using e-mail to arrange money drops and pick-ups, and even using the Internet to buy plane tickets.
"September 11 was a modern-day plot, one that could have only happened in 2001," he said.