IS CYBERWARFARE (a) one of the biggest threats of the 21st century or (b) an elaborate hoax designed to extract money from gullible governments? Stuxnet, the computer worm running rampant in Iran's nuclear facilities, tells us the answer. An analysis

of the worm by computer security company Symantec makes it abundantly clear that a few lines of malicious computer code can trip electricity grids, burn out power-station generators, pollute water supplies and sabotage gas pipelines. That cyberattacks can become real-world attacks is no longer a matter of conjecture.