WASHINGTON - Cyberspace is the battlefield of the future, with attackers already going after banks and other financial institutions and developing the ability to strike US power grids and government systems, Defense Secretary Leon Panetta said on Friday.

"We confront a whole new threat of warfare in (cyberspace).... This is an area we've got to pay close attention to. This is the battlefront of the future," he told a business group in Norfolk, Virginia.

Panetta's remarks came a week after he delivered a major policy speech on cyber security, saying the US military could act pre-emptively if it detects an imminent threat of cyber attack.

US banks and financial institutions have been under sustained attack in recent weeks by suspected Iranian hackers.

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