Australia’s 60 Minutes has aired a story on the “invisible threat” of young radicalized Muslims willing to act as individuals with no threat or warning, as was recently borne out by the Woolwich murder.
I have not been able to find the full story online, but I was sent a link to this very disturbing excerpt.
I am not sure I would characterize the threat as “invisible” as much as an issue of people turning a blind eye to it.