The "first war of the new millennium" — with its very different targets, and hence tactics — provides an excellent opportunity to make use of what has become one of the most sophisticated, but relatively unknown, corners of contemporary social science: the formal study of social networks.
The possibility that the US Administration might now be interested in this arcane branch of knowledge has already been recognized by the mainstream press. Terrorists are organized in loose, intercontinental fabrics of social relations, linked together as nodes in what have been called "cells" from Lenin to bin Laden, but which are better recognized as a group of nodes connected by links which represent the exchange of some sort of resource — ranging from information to machine guns.
For example, the effort to "follow the money" which makes terrorist activities possible is made more difficult by the existence of a covert, world wide laundering system called hawala banking in India or the Hundi system in Pakistan. This network, defined by the exchange of money, is based entirely on trust, so that no paper-trail is left behind (it is strictly a "word of mouth" network, which is what "hawala" means in Hindi). Still, once the structure of a social network becomes known, the crucial links for maintaining that structure (or destabilizing it) can be rigorously identified — no matter how distributed the power relations in it might be. In the present context, this has obvious implications — implications which have already made a number of practitioners of the networkers' art nervous about the ethics of their hard won knowledge being used by politicos in war-making mode. Still, the terrible recent events in the United States provide a rare opportunity for a much maligned profession — academic social science — to make itself useful to the society which funds it. Surely part of the answer to the question of "what now?" will be: Do formal analysis of terrorist social networks.
It is possible, however (as Martin Rees observes in an earlier posting here), that the next escalation in terrorist activity will not involve a network at all. Theoretically, a single biotechnologist with a grudge and a round-the world plane ticket could instigate a thoroughly modern Black Death. The paltry remainders of the human race might then have to go underground for generations until the surface of the Earth becomes safe for multi-cellular life-forms again. (This is, in fact, the scenario from Terry Gilliam's gripping movie, "Thirteen Monkeys".) Tor Nørretranders' suggestion to decentralize personnel would not help much in such a case. So network analysis may only work in the short run. The answer to the "what now" question is thus possibly more frightening even than what we have contemplated so far, just as driving people-laden planes into people-laden buildings seemed incomprehensible only a few short weeks ago.