Now that I think about it... it's especially ironic, given that the whole purpose of the development of the Internet Protocol by DARPA (in the original ARPANET) was to create a communications web that could survive a nuclear strike in some major cities and yet still enable basic communications throughout the rest of the (surviving) country.
The military's network can run independently of the civilian network, though, right? My friend who works in that area was telling me if something like that happened there's a way to reroute the networks pretty easily; I forget the details of his explanation, though.