(S (S (BASENP (DT The) (NNP Trident) (NN defense) (NN system)) (VP (VBD was) (VP (VBN developed) (PP (IN as) (NP (NP (NP (BASENP (NNP Britain) (POS 's)) (NN response)) (PP (TO to) (BASENP (DT the) (NNP Cold) (NNP War)))) (SBAR (WHNP (WDT which)) (S (VP (VP (VBD ended) (PP (IN with) (NP (BASENP (DT the) (NN collapse)) (PP (IN of) (BASENP (DT the) (NNP USSR)))))) (PP (IN in) (BASENP (NNP December) (NN 1991))))))))))) (PERIOD .))