In theory yes, however, in pratical terms you just need to "bomb" the right places and 90% of the communications would be gone for quite a while. Think PIX and DNS root servers, destroy those, and only minor services would be available. There are countries with a single PIX, sitting in regular rooms without any kind of security, unplug those and the whole country would be offline (to be fair, intra-ISP traffic would work). And there's no need to go that far (bombing places), a bad actor that can cut some submarine fiber in the right places would cripple the whole world. Or just someone messing up BGP config in a big ISP, no need to bomb or destroy anything, a single bad command can cause major issues worldwide (had happened before).