certain other parts of the world including places like dubai and abu dhabi, those state-of-the-art systems are actually very good at detecting the kind of explosives that groups like al qaeda in yemen are developing, even when they're concealing them inside laptops. the key technology here is called explosive trace detection technology. that involves the gate -- a laptop or some other electronic laptop device being swabbed and then a machine being used to analyze whether there's any explosive residue on that swab at all. and they can actually, these machines, detect a trillionth of a gram of residue. so they're very, very good. >> the group that is believed to have the highest level of bomb-making expertise is aqap. that's essentially al qaeda in yemen. tell us more about them and how they developed this expertise. >> al qaeda in yemen are at the center of the concern when it comes to this threat. they are significantly ahead of isis when it comes to developing