there's virtually no standoff. so when it comes to that moment of people coming through, u.s. troops have to actually check them according to the pentagon. they have to be right next to them. so if someone gets through, the ability for a bomb blast to have tremendous impact is really right there. what do they do going forward from here? well, that's really the challenge. what they have to do is figure out some way to manage that passthrough while they deal with, still, a lot of people. remember, we have about 1,000 u.s. citizens believed to still be in the country who may want to come out. and there are about 5,000 troops who still have to be withdrawn. now, we know the system is set up according to the pentagon to operate under stress, operate under -- under attack. we know it's going to have to if they want to do this successfully based on what we've seen, so far. >> tom foreman reporting there. well, there is more to come on that deadly terror attack in