It's a lot more nuanced and subtle than "One Big Attack".
Where I diverge: a Big Event is a great distraction for really 'interesting', subtle actions - and can be just as simple as the First Worm by Morris. Oooops, it wasn't meant to do that...
Things you should read or view:
- RSA Conference, 2012, On Cyberwarfare
- Fabius Maximus posts on cyberwar
- You must Be >this< Tall To Play Cyberwar (has DoD grown enough yet?)
- Cyberwar: The Pentagon Cyberstrategy
- Cyberwar: About Stuxnet, the next generation of warfare?
- Congress Authorizes Pentagon to Wage Internet War [Wired. Ryan Singel]
- M.R. on rearguard-security: Cyberwar