so first of all, you understand that we're still investigating exact circumstances. but what i can tell you is this. the attack occurred athe a gate. gate we have to check people before they get on to the airfield. the we have to ensure they're not carrying a bomb or any kind of weapon that can make its way on to an aircraft. that requires physical screening. you can't do that. you have to get very close to that person. so while the air base itself is surrounded with t walls or well bunkered in, we've done a number of things to protect ourselves. at the interface points, the gates where people actually come on the airfield, there is no substitute for a young man or woman, young united states man or woman standing up there conducting a search of that person before you let them on. the taliban conducted searches before they get to that point. and sometimes the searches are good and sometimes not. i'll note that before this attack we passed 104,000 people through. we'll evaluate what happened. but the key thing is you don't