That's part of the problem right there that people segregate into enclaves and have little contact with each other's communities.
Edit: getting more downvotes, without any of the downvoters caring to justify them so far, so I can only speculate as for the reasons behind them.
I'm wondering if the downvoters (I'm guessing from the USA) are aware that my views are already a law in many of the liberal democracies of Europe? There are laws which put you in jail for saying certain things, and they are enforced (there are people who are doing time just for saying things).
Meanwhile, people are dying. That is exactly how some people see it, and exactly how I see it. I'm not emotional, I'm logical, and I expect government to protect us from evil individuals/groups. Arguably, it's not there to foster some sort of "long-term" sustainable co-existence between different cultures.
First, you establish security and root out potential problem groups. And once that's happened, and you have almost non-existent danger to the local populace, then you can start worrying about integration and grey-goals such as "peaceful coexistence" and "de-radicalization". And I don't say that as a means to single-out immigrants, or foreign groups. This reasoning should apply just as much to dangerous elements that are within, and part of society currently.
- Bringing more eyes and ears in the form of social workers and community policemen in problematic neighborhoods.
- Provide better education/work opportunities for immigrants.
- Better cooperation between municipalities and Muslim organisations/mosques.
- Deradicalization programs.
Of course, implementing such policies takes time and it's much more popular to present the 'easy solutions' (more surveillance, closing borders, etc.).
France has been doing pretty much the opposite, investing money in surveillance and special forces instead. Belgium has kind of ignored problems.