threats we face from the airline aviation sector is the idea that has been reported of these nonmetallic ieds that can be built and taken onto airplanes. remember, these people are coming not just from the middle east but europe, the united states, from australia. they have legal travel documents to track outside the region. it's easier to get to than afghanistan and pakistan. now it's the biggest training ground, far surpassing what we saw in afghanistan and pakistan. so that's why i view it as the biggest threat. >> i know you have to be careful here, sir. we know there have been americans who have gone to fight in syria. for all we know, maybe they're crossing into iraq. do you have concerns these americans may be receiving this bomb making training from al qaeda in the arabian peninsula that they may carry it back here to the homeland? it's a serious concern because they can't come back into the united states or get on a flight inbound to the united states. with tiers that may not be