They are also trying to stir up distrust between Muslims and non-Muslims so there is no cooperation to defeat them. Ultimately, I don't think they will be successful. Right after these events take place, there are rallies where Muslims come out to show their solidarity and support of the community and efforts to put an end to this kind of atrocity. It is just very difficult to determine who is a likely candidate to commit these acts. For instance, the young man who killed himself was on a watch list of about 500 people but was not deemed to be an immediate threat. The bottom line is the authorities cannot watch everyone, so perhaps there is some policing that could (or maybe already does) take place by members of the communities themselves, assuming they trust the authorities enough to report. Bottom line - there is no easy solution. We just have to hope sanity rules in the end. I certainly do.