Pentagon: The global cyberwar is just beginning

The Pentagon is rapidly preparing for cyberwar in the face of alarming and growing threats, say senior defense officials, who add that sophisticated attacks have prompted them to take the striking step of investigating the feasibility of expanding NATO's collective defense tenet to include cyberspace.

But as such planning intensifies, the military is struggling with some basics of warfare - including how to define exactly what, for starters, constitutes an attack, and what level of cyberattack warrants a cyber-reprisal. Equally tricky, defense officials say, is how to pinpoint who is doing the attacking. And this raises further complications that go to the heart of the Pentagon's mission.