Ake - You have put matters in the correct perspective.
There is amongst some, and only a few, 'Catters a knee-jerk anti Americanism/Anti Bush reaction. Some of those few who seem to only inhabit the BS posts to their sole satisfaction.
Negotiation and dialogue should work to remove the causation of violence and terrorism. This assumes the 'other side' wishes dialogue.
In the case of 'Ultras' there seems to be no wish for any negotiation or dialog.
What I think you did not point out was that it only requires a very small percentage of any religious or racial mass to provide an effective "terrorist/freedom fighter" nucleus.
Given the latest press reports of 10,000 + al-quaida 'warriors! Waiting to seek death that then that represents a miniscule percentage of the Middle Eastern Muslim population. Unfortunately, and even given gross exaggeration, that represents sufficient cadre to perform the odd nasty or so.
If I remember correctly, tho I cant recall the source, French Government figures suggest that only 2% of the French population supported actively, or passively, the French resistance movement in the 1940's. That is when they were not betraying rival groups to the Milice or the Gestapo. The French Governments are not prone to playing down the "Resistance". Even these days 60 years later too many political reputations depend upon it. It has been argued, and I do not necessarily believe it, that the French Resistance did more to destroy lines of communication than the RAF and USAAF.
The down side is that over reaction can occur- but would you be the Minister of any Government explaining a major loss of life on the grounds we did not see it as a serious threat ?? Any politician could not ignore this.
A point you do not mention is the "Poor little Rich Kid" syndrome - After all the 9/11 hijackers (if they were accurately identified) were not exactly impoverished, out of the refugee camps - But then. if reports are correct, neither is Bin-Laden.
A parallel in the British left might be the Second Viscount Stansgate, The Redgraves, Sir Richard Acland Bart. Tam Dayall of the Binns (an old Scottish title) and others of that kidney. Or in Germany, the Bader- Mienhof collective (SP).
My particular rule of the thumb is simple, the greater the distance from the working class, the further to the 'left', and reality.