(S (S (BASENP (NNS Observers)) (VP (VP (VBP have) (VP (VBN noted) (SBAR (IN that) (S (BASENP (DT the) (NN summit)) (VP (VBZ has) (VP (VBN attracted) (NP (BASENP (DT the) (NN participation)) (PP (IN of) (NP (NP (BASENP (NNP Saudi) (NNP Arabia)) (CC and) (BASENP (NNP Syria))) (PRN (COLON --) (NP (BASENP (NN two) (JJ Arab) (NNS states)) (SBAR (WHNP (WDT that)) (S (VP (VP (VBP do) (RB not)) (VP (VB recognize) (BASENP (NNP Israel))))))) (COLON --))))))))))) (CC and) (VP (VBP say) (SBAR (IN that) (S (BASENP (DT this)) (VP (VBZ is) (ADJP (JJ critical) (PP (TO to) (NP (BASENP (NNS chances)) (PP (IN for) (BASENP (NN success)))))))))))) (PERIOD .))