Iran

Security professionals in both the U.S. government and in private industry have long feared the prospect of a cyberwar with China or Russia, two states capable of launching destructive attacks on the computer networks that control critical assets such as the power grid or the financial system.

Now they face a new cyberthreat: Iran.

"[The Iranians] have all the resources and the capabilities necessary to be a major player in terms of cyberwarfare," says Jeffrey Carr, an expert on cyberconflict who has consulted for the U.S. Department of Defense.