explosives. they are using drones. they are trying to build their own planes. they have been fryitrying to bua self-driving car. all the resources and the brain power that they have is being funneled into efforts to come up with the next most deadly tactic that they can get their hands on. wolfle? >> the airport security systems, there are various degrees, some are pretty good and some are great and some not so good and that's the problem. >> and, okay, you know the achilles' heel in the system is what you need to worry about, the weak link in the chain. it does occur to me, wolf, if we're forcing all the devices into the baggage hold, many of them have the lithium ion batteries which is a huge fire risk and having them in the hold exposes the aircraft to another kind of ring. the other point that evan brought out that would be difficult to detonate is in the hold, pan am flight 103 is what i would offer you as counterpoint of that, december of 1988.