Destruction is the last thing a military wants to accomplish with a communications network. A military only wants to shut down an enemy's network if it isn't acquiring useful information. The best thing is to infiltrate enemy computers and networks, spy on them, and surreptitiously disrupt select pieces of their communications when appropriate. The next best thing is to passively eavesdrop. After that, perform traffic analysis: analyze the characteristics of communications. Only if a military can't do any of this would it consider shutting the thing down. Or if, as sometimes but rarely happens, the benefits of completely denying the enemy the communications channel outweigh the advantages of eavesdropping on it.

Cyberwar is certainly not a myth. But you haven't seen it yet, despite the attacks on Estonia. Cyberwar is warfare in cyberspace. And warfare involves massive death and destruction. When you see it, you'll know it.