NEW : Airline CEO says situation being monitored , does n't comment on flights . Al-Shaabab militants threaten flights with statement , graphic on African Union . `` All I can say is we 're monitoring the situation very closely , '' Leedham said . Web forces spokesman says he 's not received official warning . Al-Shaabab 's group is seeking to oust Islamist forces from U.S. .
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 . Al-Shaabab 's group is seeking to oust Islamist forces from U.S. .