An examination by Reuters, including dozens of interviews with military officers, government officials and outside experts, shows that the U.S. military is preparing for digital combat even more extensively than has been made public. And how to keep the nation’s lifeblood industries safe is a big, if controversial, aspect of it.

“The best-laid defenses on military networks will matter little unless our civilian critical infrastructure is also able to withstand attacks,” says Deputy U.S. Defense Secretary William Lynn, who has been reshaping military capabilities for an emerging digital battlefield.

Any major future conflict, he says, inevitably will involve cyber warfare that could knock out power, transport and banks, causing “massive” economic disruption.

But not everyone agrees that the military should or even can take on the job of shielding such networks. In fact, some in the private sector fear that shifting responsibility to the Pentagon is technologically difficult — and could prove counterproductive.