First of all, seeing 'them' as evil, ugly, bad, etc., precludes understanding. And without understanding, no remedy is possible. To begin with, one person's terrorist is another's noble warrior. Historical examples abound so I leave there. Plunging deeper....

We all inherit varying degrees of social responsiveness which determines our ability to feel group identity. While most people are able to feel enough of this connection in civilization, others need a smaller scale and more intimate tribal setting than civilizations offer. Besides this, ideology regardless of its name, plays a fundamental role in fulfilling this need and in rationalizing any ensuing actions. The simple back and white ideologies are the most effective, whether they are Nazi, Communist, Christian, Islamic, or Jewish, etc.

Other ideologies, like Buddhism, offer less suitable rationalizations. They are more introspective; there is no evil villain out there role - no 'capitalist pigs', 'inferior races', 'infidels', 'devils', 'unsaved sinners'... etc. Ah, but nevertheless, people in Buddhist cultures still find a rationalization to kill when they need one.

Truly, the emotion comes first, then we grasp whatever ideology or simple rationalized excuse to support it. Yet, many blame the ideology - religious ones being a favorite. Why? We seem to instinctively take life at face value, for one thing. But I digress. Emotion is key. Our tribal biology hungers for social connection - sports, family, government, religion, business, education, etc., all play themselves out in a tribal context. (Sure, a suit and tie looks difference than the tattoos of an African tribe's man, but,...)

Young people who do not feel an 'appropriate civilized' sense of tribal connection are the willing recruits for charismatic megalomaniacs of every stripe. The process is the same, only the surface rationalizations vary. Simply put, hooliganism is a symptom of tribal disaffection from civilization.

Thus, the remedy for terrorism, and related 'gang' activity of all types, is easy. These atavistic behaviors will disappear the instant people have a sufficiently intimate connection with each others. Mmmm... it is a little hard figuring out how to put this knowledge into practice, eh? How shall we begin this journey? After all, civilization causes this sense of disconnection, and we're not going to dump civilization. Although, it wouldn't hurt to reduce the size and population of the state. In any case, as Buddha suggested, Right Understanding is a fine place to start. And one day the people will all say, 'It happened to us naturally.'