(S (S (BASENP (JJ Islamic) (NNS militants)) (VP (VBP have) (VP (VBN vowed) (S (VP (TO to) (VP (VB fight) (NP (BASENP (NNS pirates)) (VP (VP (VBG holding) (BASENP (DT the) (ADJP (JJ Saudi) (JJ Arabian)) (NN oil) (NN tanker) (NNP Sirius) (NNP Star))) (PP (IN off) (BASENP (DT the) (JJ Somalian) (NN coast))))))))))) (PERIOD .))