@luhe
Correct - they might might be perfectly sane just completely indoctrinated. The use of the term "mental" is relative. Anyone who is prepared to cut off the head of an aid worker just because of political and religious ideals is mental even if they don't have a medically definable mental illness.
I'm not questioning the principle of a military role, just that the solution has to be a complete change in attitude of the majority of people. The end of the troubles in Northern Ireland was essentially because the majority of people got tired of living in an urban war zone. Their ideals were trumped by their desire to have a normal life and the moderate voices started to outweigh the extremists.
The Israel/Palestinian issue and the West/extreme Islam conflicts are no where near this tipping point but will be one day I hope. The other problem is that all the wannabe jihadi lunatics are only too pleased to be squashed like a bug. Take away an afterlife full of virgins and then see how many of them want to blow themselves up...