Barking up the wrong tree in an infinite forest

I'm beginning to think that the real strength of terrorism is the fact that its targets can be diversified faster than countermeasures. Whatever is hardened or checked or monitored, there will always be something else. Probably because the nature of terrorism is to use the social infrastructure as a weapon - trains are of course a near perfect way of placing your explosives at a given time, in fact at given times, into a concentration of people. And they even publish timetables. God forbid anyone has a go at the utilities - power, gas, water... (In fact we may already have narrowly escaped a mass water attack. When I were a lad, a deranged citizen of Leeds whose psychosis included an obsession with Hitler prepared to add cyanide to Eccles Reservoir before being arrested for an unconnected murder.) Not so long ago I was told by a former naval person that maritime terrorism was rare "because it's difficult, and the oil in a tanker won't explode". (We'll set aside the vapour in the empty tanks) He did concede the possible vulnerability of a liquid petroleum gas tanker - they come from Algeria and would explode with the power of a small nuclear warhead - but, to my mind, didn't really imagine it could happen. I wonder if we are committing the fallacy of trying to solve social, mental problems with hardware.

Mind you, this is where the historical fallacy of taking either side in the structure/free will debate bites - whatever the deep social forces bubbling and heaving suggest, a different action would so often have changed life entirely. If it's foolish to believe (say) that had Gavrilo Princip been unable to shoot straight, the world would have remained at peace, it's equally foolish to imagine that the 2000 US presidential elections were entirely defined by inevitable economic and demographic shifts, or that the development of population structure in the Middle East would have meant much if the suicide hijackers had been searched at Boston airport. History can be seen as a struggle between those vast narratives, megatrends, and the perpetual and equal power of accident and defiance. In this case, Al-Qa'ida's addiction to deep history - the Spanish Reconquista as equally pertinent as the Gulf War - set against its true enemy, the security guards and cops, cleaners and track inspectors most likely to foil them. What is the point? Probably that although defensive measures (taking away dustbins, installing radiation detectors at the container wharves of Felixstowe) are certainly of value, and that offensive ones may also help, terrorism can only in the end be contained, managed, endured. It's usual that any terror group with a sufficient base of support can only ever be kept in bounds - victory is impossible. With traditional terrorists, this was the moment of negotiation. That would have been the course I would have suggested for Spain, but if the Madrid massacre is Eta's work, I wonder if it is still possible? Have they not joined the new terrorists, Walter Laqueur's postmodern terrorists - no concrete aims, or wildly impossible ones, like that of reversing the last 400 years of history and revolutionising the world, reconquering the lost and, I'm sure, ungrateful kingdom of al-Andalus.