There is considerable disagreement over that, with some experts saying both that an attack is likely and the defense is possible, while others dismiss both.

Nobody in government or in cybersecurity thinks Iran is capable of delivering any kind of serious military blow to the U.S. But some say it could damage computer networks that control critical American assets like the power grid or the financial system.

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

The NPR report also said that James Clapper, director of national intelligence, told Congress that Iran is motivated to attack the U.S. and that its cyber capabilities have, "dramatically increased in recent years."