NORAD officials have maintained that they would have intercepted and shot down United 93.
( ( NORAD officials ) ( ( have ( maintained ( that ( they ( would ( have ( ( ( intercepted and ) shot ) ( down ( United 93 ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP NORAD) (NNS officials)) (VP (VBP have) (VP (VBN maintained) (SBAR (IN that) (S (NP (PRP they)) (VP (MD would) (VP (VB have) (VP (VBN intercepted) (CC and) (VBN shot) (PP (IN down) (NP (NNP United) (CD 93)))))))))) (. .)))
NORAD would have sent their fighters to take out the engines of United 93.
( NORAD ( ( would ( have ( ( sent ( their fighters ) ) ( to ( ( take out ) ( ( the engines ) ( of ( United 93 ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP NORAD)) (VP (MD would) (VP (VB have) (VP (VBN sent) (NP (PRP$ their) (NNS fighters)) (S (VP (TO to) (VP (VB take) (PRT (RP out)) (NP (NP (DT the) (NNS engines)) (PP (IN of) (NP (NNP United) (CD 93)))))))))) (. .)))