Evolution and terrorism
People tend to be risk averse - that is, they will shy away from risks even when the objective odds against something bad happening are quite long. Put another way, we have Sod's law hard-wired into our brains. What can go wrong will go wrong. If something bad can happen, it will happen to me.
Thus, many people are now afraid of being sumarrilly executed by anti-terrorist police. There's 7.5 million people in London, your chances of dying at either the hands of the police or bombers are so slim as to make your chance of life excellent. But, as evolution tells us, million to one shots happen to us. And I can only die once.
Obviously, communities that have experienced racism, or believe themselves to be the target of suspiscion will feel their aversion to risk the more. Something that - I would suggest - will be aggravated by the fact that we are hardwired for face perception - that the threat can be associated with a facial type means that racism could well result.
Again, recognising faces is a strong part of our evolutionary strategy, and may be one reason why racism has been so able to take root. Slight differences in faces convey vast information to humans - when we would be alike to sheep as sheep (who can recognise each others' faces) would be to us.
Upshot, victory for the terrorists.
War is about imposing your will on your opponents. Imposing costs, in terms of terrorists is a first goal.
But, more than that. The home front for any war is a source of violence. Warring powers must coerce and coraal populations, birfurcate and divide their camp from the enemy's - destroy any hope of collaboration.
The terrorists have imposed a wedge, it is getting harder to pull it out, that wedge will, unless care is taken, become a recruiting sergeant. In the meanwhile, risk averse people surrender precious freedoms for the sake of avoiding a slim chance of violent death.