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 [General Arnold].
( 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 ( -LSB- ( General ( Arnold -RSB- ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (CC But) (NP (PRP we)) (VP (VBP know) (SBAR (IN that) (S (PP (IN at) (NP (CD 10:31))) (, ,) (NP (NNP General) (NNP Larry) (NNP Arnold)) (VP (VBD instructed) (NP (PRP$ his) (NN staff) (S (VP (TO to) (VP (VB broadcast) (NP (DT the) (NN following)) (PP (IN over) (NP (DT a) (JJ NORAD) (JJ instant) (NN messaging))) (SBAR (S (NP (CD 10:31) (NNP Vice) (NN president)) (VP (VBZ has) (VP (VBN cleared) (PP (TO to) (NP (PRP us))) (S (VP (TO to) (VP (VP (VB intercept) (NP (NP (NNS tracks)) (PP (IN of) (NP (NN interest))))) (CC and) (VP (VB shoot) (NP (PRP them)) (PRT (RP down)))))))))) (SBAR (IN if) (S (NP (PRP they)) (VP (VBP do) (RB not) (VP (VB respond) (PP (IN per) (NP (NNP -LSB-) (NNP General) (NNP Arnold) (NNP -RSB-))))))))))))))) (. .)))
General Larry Arnold told his staff to broadcast over a NORAD messaging service at 10:31 that the Vice president had authorized the shooting down of hijacked planes, they did so immediately.
( ( ( General ( Larry Arnold ) ) ( told ( his ( staff ( to ( ( ( broadcast over ) ( ( a ( NORAD ( messaging service ) ) ) ( at 10:31 ) ) ) ( that ( ( the ( Vice president ) ) ( had ( authorized ( ( ( the shooting ) down ) ( of ( hijacked planes ) ) ) ) ) ) ) ) ) ) ) ) ) ( , ( they ( ( did ( so immediately ) ) . ) ) ) )
(ROOT (S (S (NP (NNP General) (NNP Larry) (NNP Arnold)) (VP (VBD told) (NP (PRP$ his) (NN staff) (S (VP (TO to) (VP (VB broadcast) (PRT (RP over)) (NP (NP (DT a) (JJ NORAD) (NN messaging) (NN service)) (PP (IN at) (NP (CD 10:31)))) (SBAR (IN that) (S (NP (DT the) (NNP Vice) (NN president)) (VP (VBD had) (VP (VBN authorized) (PP (ADVP (NP (DT the) (NN shooting)) (RB down)) (IN of) (NP (JJ hijacked) (NNS planes))))))))))))) (, ,) (NP (PRP they)) (VP (VBD did) (ADVP (RB so) (RB immediately))) (. .)))