i covered chat rooms and this is where a lot of the hatred, ideology is spread through those chat rooms and people logging onto the game and talking to people across the world and sort of building a strategic plan if you like to travel to syria. that's one of the ways. we know that isis is hugely prolific in using social media and twitter and facebook and we've just got to jump onboard in terms of intelligence in the way we address this. >> hearing from one main news organization, this hostage taker has been arrested before for extremist activity. they know who he is and what it's about. >> you have to get into the loop. we want to prevent people from getting radicalized in the first place. if they do get radicalized, we want to find out about them. it's a policing question. ultimately also it's a resilience question.