We need to do a better job at integrating them (both from social and policing point of view). This is an expense but is less an expense than doing war at foreign country.<p>Unfortunately, multiculturalism has often been used as an excuse for not doing enough. Many times I have heard police to say (about some atrocity that happened in some subculture) that this is &quot;how they do things in their culture&#x2F;community&quot;. It&#x27;s unacceptable excuse for not doing the job.<p>Appeal of radicalism is ultimately a social issue like many others (say, appeal of drugs, appeal of violence), and it should be dealt with as such. People on the right don&#x27;t like the idea of telling somebody what to do at someone else&#x27;s expense, but I am afraid that good prevention (access to education, having good job) is the only thing that really works here.<p>Whether citizens will accept the above is of course up to them, but I am convinced (from empirical evidence) that this is the best way to handle the problem in open society. If, on the other hand, the goal is to remove as much terrorism as possible, then the open society is perhaps no good. If you close off borders, have isolationist foreign policy, and establish a semi-totalitarian regime, you will probably get less terrorism (this was case of Czechoslovakia in the past). But this strategy probably comes with its own set of disadvantages (according to this list <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;List_of_countries_by_immigrant_population" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;List_of_countries_by_immigrant...</a>, the only country that seems to be worth immigrating into with low amount of immigrants is Japan).