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Guarding water wells and granaries from enemy raids is as old as war itself. In the Middle Ages, vital resources were hoarded behind castle walls, protected by moats, drawbridges and knights with double-edged swords.
Today, U.S. national security planners are proposing that the 21st century's critical infrastructure — power grids, communications, water utilities, financial networks — be similarly shielded from cyber marauders and other foes.
The ramparts would be virtual, their perimeters policed by the Pentagon and backed by digital weapons capable of circling the globe in milliseconds to knock out targets.
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.