U.S. Defense Secretary Leon Panetta says cyberspace is the battlefield of the future.
Panetta's remarks came a week after he delivered a major policy speech on cyber security, saying the U.S. military could act preemptively if it detects an imminent threat of a cyber attack.
U.S. banks and financial institutions have been under sustained attack in recent weeks by suspected Iranian hackers.
A group calling itself the Cyber Fighters of Izz ad-din Al Qassam has claimed credit for the disruptions, calling them a protest against an anti-Islam video, "Innocence of Muslims," which was posted on YouTube and has provoked violent protests across the Muslim world.
Based on reporting by Reuters and AFP