All societies have a background "loony" rate. Many of them want to kill the general public many want to kill other groups of "loons".

The more that can be facilitated to undertake "care in the community" abroad with hopes, dreams, and a second hand assault rifle who with any luck won't return home the better - rather they kill and be killed over there rather than undertake massacares over here - if the Oslo chap had been bough a ticket alongside those two persons who killed a soldier with a machete in the street the world would be a slightly better place.

The Foreign Legion is another great rehabilitation for past offenders who are slightly less loony - take all comers and at the end of it a clean sheet. Why on earth a criminal record precludes joining an organisation which practices killing people is beyond me.