(S (S (BASENP (JJ Several) (NNS analysts)) (VP (VBP have) (VP (VBN suggested) (SBAR (IN that) (S (BASENP (DT this) (ADJP (RBS most) (JJ recent)) (NN ceasefire)) (VP (VBZ is) (VP (VBN based) (PP (IN on) (NP (NP (BASENP (NNP ETA) (POS 's)) (NNS tactics)) (VP (VBG causing) (S (NP (BASENP (PRPD their) (NN support)) (PP (IN in) (BASENP (DT the) (NNP Basque) (NN region)))) (VP (TO to) (VP (VB plummet)))))))))))))) (PERIOD .))