I agree with walrus. After reading the paper, I was struck by how restrained the authors were. In the words of one of them, they wanted to avoid the dangers of sociological determinism. While none of them missed the opportunity to display their knowledge of historical detail and make idiographic generalizations, the only reason they gave for avoiding sociological generalization was that the Internet and the media have changed things. Frankly, I don't like this whole "mutation" analogy. If something's anomalous, then there has to be a pattern and trend. If terrorism is a symptom, then there has to be a cause. Discover the pattern, find the cause, fix the problem. Perhaps the authors were blindsided by a mandate to sound like fortune tellers. I tell ya, though. I'm gaining more respect for Gunaratna. I used to think he was a bit alarmist, but he wrote a pretty solid piece here.