    Sentence 1: But we know that at 10:31, General]  Larry Arnold instructed his staff to broadcast}  the following over a NORAD instant messaging}  10:31 Vice president has cleared to us to  intercept tracks of interest and shoot them]  down if they do not respond per [Gener  Arnold).    Sentence 2: General Larry Arnold told his si   to broadcast over a NORAD messaging service]  at 10:31 that the Vice president had said to  loff on shooting down any hijacked planes ui  the President could be reached.