NEW : Airline CEO says situation being monitored , does n't comment on flights . Al-Shaabab militants threaten flights with statement , graphic on African Union . Web forces spokesman says he 's not received official warning . `` We have taken precautionary measures , but that 's all we can do , '' Ba-Hoku told CNN . Barigye Ba-Hoku group is seeking to oust Ugandan forces from Ethiopia .
NEW : Airline CEO says situation being monitored , does n't comment on flights . Al-Shaabab militants threaten flights with statement , graphic on African Union . Web forces spokesman says he 's not received official warning . Barigye Ba-Hoku group is seeking to oust Ugandan forces from Ethiopia .