those are the ones we know of. what we've seen with tlelts like in san bernardino is a number of individuals are staying below law enforcement's radar and those that re don't know of. this is a challenge. what also happens is, isis is in a very sophisticated way in a cell in raqqah, syria, sending out these messages, seeing who takes the bait, seeing who retweets. then they start doing private messaging. if they think they have someone serious who might want to plot something sophisticated, they then go dark. it goes into one of these encrypted apps. this is unprecedented. this the first time in history even with a warrant, law enforcement cannot get access to the content of that communication. it's a complicated issue because some of these companies are not american and they're overseas. it's the ying yang of technology. we also have increasing cyber attacks and people want to keep their information secure. so, we've got to figure out how to solve this problem because we've got to keep ourselves safe from the cyber attacks and from the terrorists. >> quickly, the front-runner in