All this is known, but what is interesting is that a former head of the Swedish truck-maker Scania, a Mr. Leif Ostling, has said Sweden is headed for civil war because of the problem of its violent migrants who have no inclination to integrate into Swedish society. As a successful businessman, his views can't be dismissed as being from some sort of antisocial loon living in his mother's basement.
This raises the question: how do you have a civil war in this day and age? Having a civil war is aspirational, but is it achievable?
The population of Sweden is now 10.1 million, of which 8% are of the Islamist persuasion. The first question is, who owns the guns, and how many are there?
This site says civilians in Sweden are estimated to hold 2,296,000 guns, legally and illegally, of which about half are rifles. There is a big hunting tradition in Sweden. As of the year 2011, licenced firearms per 100 head of population was 6.5, and registered guns per 100 people was 18.9. So the average gun-owner has three of them.
Comment: See: Triumph of the right in Sweden is a result of the total failure of liberalism