kind of armament in its arsenal. it is not clear. this sort of devices that not -- has not been used seen or reported in afghanistan and the taliban have had a lot of time to go after afghan helicopters and u.s. military aircraft and this type of surface-to-air missile has not been used. but going forward, that will become it has to be part of the evaluation and i will stress again that there is no evidence to support that they exist. but the concern by security experts, western security experts about the situation in afghanistan, that has been expressed to me over recent months, kate. >> nick, thank you for your reporting. let me bring in now cnn's tim lister. you have done extensive reporting on the intelligence and the threat stream that is existed that you've been hearing from officials. the threat stream from isis-k targeting people outside of the airport. talk to us through your