In part, the Pentagon intends its plan as a warning to potential adversaries of the consequences of attacking the U.S. in this way. "If you shut down our power grid, maybe we will put a missile down one of your smokestacks," said a military official.
One idea gaining momentum at the Pentagon is the notion of "equivalence." If a cyber attack produces the death, damage, destruction or high-level disruption that a traditional military attack would cause, then it would be a candidate for a "use of force" consideration, which could merit retaliation.
"A cyber attack is governed by basically the same rules as any other kind of attack if the effects of it are essentially the same," Gen. Dunlap said Monday. The U.S. would need to show that the cyber weapon used had an effect that was the equivalent of a conventional attack.
For instance, if computer sabotage shut down as much commerce as would a naval blockade, it could be considered an act of war that justifies retaliation, Mr. Lewis said. Gauges would include "death, damage, destruction or a high level of disruption" he said.
