Yes, Iam64, I wondered, as well, although I didn't see the original documentary. I wondered also why, at the very least, the participants were not at the top of the terror watch list. Someone previously used "tentacles" to describe these sub-groups. Undoubtedly, they are now so numerous ( and able to sprout seemingly spontaneously) that, as has been stated, our police force is too overstretched to deal with all the possibilities, despite their good work.
I understand the legal reasons, but am dismayed this morning, by the number of suspects that have been released without charge.