(S (S (BASENP (JJ Syrian) (NNS rebels)) (VP (VBP have) (VP (VP (VBN threatened) (NP (BASENP (NN retaliation)) (PP (IN against) (BASENP (DT the) (NNP Hezbollah) (NN group))))) (PP (IN for) (S (VP (VP (VBG sending) (BASENP (NNS fighters))) (S (VP (TO to) (VP (VB assist) (NP (BASENP (NNP Syrian) (NNP President) (NNP Bashar) (NNP al-Assad)) (COMMA ,) (SBAR (WHNP (WP who)) (S (VP (VBZ is) (VP (VBG fighting) (S (VP (TO to) (VP (VB end) (NP (BASENP (DT a) (NN revolt)) (PP (IN against) (BASENP (PRPD his) (NN rule))))))))))))))))))))) (PERIOD .))