Strategy Page calls it a disease.
This new disease manifests itself when an event, or government propaganda, stirs up nationalistic feelings among many Internet users. There then follows much chatter on message boards, email, messaging and so on. This quickly evolves into the organizing of online vigilantes. Nationalistic hackers proceed to do damage to any available target of these nationalistic feelings. Often there isn’t a target, as in the case of a natural disaster, where the mobilized net users concentrate on helping out. But when the news event involves another nation, or person, there follows hacking attacks, of varying degrees of intensity, against the designated “enemy.”
I don’t think nationalism is a disease. I’m an American nationalist myself. What SP is describing is what the American eResistance, a combination of psychological operations and computer network attack by civilian irregular information operators, will look like. We have much to learn from the Chinese, Grasshopper.