been invisible to us in the way they are communicated. just because they have not communicated or touched in a place that we can see them. and knowing there are needles out there that you can't see is very worrisome. >> is that now a bigger threat to the u.s. homeland than al qaeda? >> yes. the threat that isil presents and poses to the united states is very different in kind in type and degree than al qaeda. isil is not your parent's al qaeda. it's a very different model. and by virtue of that model, it's currently the threat we are worried about in the homeland most of all. >> why is isis so powerful? >> well, they have adopted a model that takes advantage of social media in a way to crowd source terrorism. they have invested about the last year in pushing a message of poison, primarily through twitter, but other parts of social media that is a silent song with two dimensions. they are preaching through social media to troubled souls urging them to join their