You're absolutely right, re: distancing ourselves from them doesn't help one bit. Just look at christians, all day going 'but that's not TRUE christians' and failing to do anything about the fringe crowd, who is left free to rampage and harm everyone else. Muslims have this problem too - too much denial of them coming from the same place but interpreting things differently, not enough real action to do anything about it (although to be quite fair, I think there's many mosques in the west where they do keep an eye out for it, extremism being such a prominent problem these past couple decades).
Extremism of any kind is always an internal problem, since outside interference can make it very much worse. Which just means that the only people who can safely handle it are the people in the same community.
The problem of course being, just what needs to be done to handle it properly. The only thing crystal clear is that the only way to deal with the problem is to engage with the problem.