(S (S (S (SBAR (IN While) (S (NP (BASENP (DT the) (NN threat)) (VP (VBN received))) (VP (VBD covered) (BASENP (RB only) (NN oil) (NNS tankers))))) (COMMA ,) (S (BASENP (JJ other) (JJ large) (NN cargo) (NNS ships)) (VP (VP (VBD were) (ADVP (RB also))) (PP (IN at) (NP (BASENP (NN risk)) (PP (IN of) (BASENP (NN attack)))))))) (COMMA ,) (S (BASENP (JJ naval) (NNS officials)) (VP (VP (VBD went) (PRT (RP on))) (S (VP (TO to) (VP (VB say))))))) (PERIOD .))