they need to go, where they need to have their gear. but most importantly what role that they do in a war fighting environment. reporter: wait yacpatriot mi batteries defend the base from north korean ballistic missiles. preparations for chemical attacks are constant. airport crews hone their readiness. we ve been granted rare access to the air operation centers deep underground, the place where north korean missile launches are first detected. this facility is so critical, war planners say it is the number one target of the north if hostilities break out. thus, what we are showing you is highly restricted. suffice to say, layers of censors give american and south korean operators a very detailed view of threats that they ll have minutes to react to. whether you see missile launch in the north, you have to know whether it is coming here oreoul o goi harm else into sea prett quickly. we do. time of flight is pretty short but we have great capabilities all throughout this peninsula