(S (S (BASENP (DT The) (NNP U.S.) (NN government)) (VP (VBZ has) (VP (VBN maintained) (SBAR (IN that) (S (BASENP (NNP Al-Qaeda)) (VP (VP (VBD orchestrated) (BASENP (DT the) (NNS attacks))) (PP (IN under) (NP (BASENP (DT the) (NN leadership)) (PP (IN of) (BASENP (NNP Osama) (NNP bin) (NNP Laden))))))))))) (PERIOD .))