Indeed, an elderly woman allegedly took down the Internet in large measure in three countries:
A 75-year-old Georgian woman was despondent following her arrest and subsequent release for alleged cutting a fiber-optic cable in her poverty-stricken village of Armazi -- and causing Internet outages in three neighboring countries.
Somebody hacked through the cable, in any case. Sure, Georgia, Azerbajian, and Armenia don't have the most redundant system. But the point is, the Internet can be attacked. If a single person with a shovel can knock out the Internet in these countries--by accident, what could determined attackers do to America? Or China, for that matter?
When we speak of combating cyber-warfare, I just don't think we should forget that smart bombs can be used to counter-attack cyber-warriors in the real world.