The Pentagon has confirmed that a cyber attack against computer networks in the United States could prompt a retaliatory military strike.
"It would be irresponsible, and a failure of the Defense Department's mission, to leave the nation vulnerable to a known threat," Deputy Defense Secretary William Lynn explained during a recent briefing about the DoD's new cyber strategy.
"[As such], the United States reserves the right, under the laws of armed conflict, to respond to serious cyber attacks with a proportional and justified military response at the time and place of our choosing."
However, Lynn said the DoD's cyber strategy ultimately emphasized "denying the benefit of [an] attack."
"If an attack will not have its intended effect, those who wish us harm will have less reason to target us in the first place," Lynn said.
He noted that any response to a cyber offensive would be "dictated by the effect," rather than location.
Concurrently, the president would "consider all the tools he has" if the attack caused significant damage - such as human casualties and massive economic losses.
Meanwhile, James Lewis, a senior fellow at the Center for Strategy and International Studies, told Politico it's the president "who gets to decide" if the cyber strike is a war or "something else."
"The standard is ambiguous. Deciding when something is an act of war is not automatic. It's always a judgment," he added.