The US may soon classify major cyber attacks as acts of war, which may face possible military retaliation.

Classifying computer sabotage, coming from another country as constituting an act of war is likely to be unveiled in Pentagon's first ever cyber strategy, the Wall Street Journal reported, quoting from unclassified portions of the strategy expected to become public next month.

The threat of military retaliation, the paper said, was to serve as a warning to foes not to mess with or sabotage US nuclear reactors, subways, country's electricity grid and pipelines.

"If you shut down our power grid, maybe we will put a missile down one of your smokestacks," said a military official.

The paper said the recent cyber attacks on the Pentagon systems - as well as the sabotaging of Iran's nuclear programme via the Stuxnet computer worm?have given new urgency to US efforts to develop a more formalised approach to cyber attacks.

WSJ quoting officials said the new strategy would maintain that the existing international rules of armed conflict - embodied in treaties and customs - would apply in cyber space.

While refusing to discuss potential cyber adversaries, officials told WSJ the previous hacking attacks on strategic US offices had originated from Malaysia and China.

"That's why military planners believe the best way to deter major attacks is to hold countries that build cyber weapons responsible for their use," the paper said.

A parallel, officials said, existed in President George W Bush administration's policy of holding foreign governments accountable for harbouring terrorist organisations, a policy that led to the US military campaign to oust the Taliban from power in Afghanistan.