As far as the Security police gathers, these people travel on their own initiative and with their own money, and not with the support from any "official mosque".
One way for Säpo to gather information is to hold what they call "voluntary talks" with people they think might be about to go. Säpo has been criticised for this, by people who feel singled out as guilty, since the talks are held with many more than actually go.
Malena Rembe says that these talks has little effect to stop the trips, since "those who do want to go, will do so sooner or later anyway". The talks are however held because Säpo has been tipped off and, says Rembe, "we need to give the person in question the chance to comment".