(S (S (S (BASENP (NNP North) (NNP Korea)) (VP (VBZ claims) (SBAR (S (BASENP (PRP it)) (VP (VBZ has) (BASENP (NN nuclear) (NNS weapons))))))) (COMMA ,) (SBAR (IN although) (S (BASENP (DT this)) (VP (VP (VBZ has) (RB not)) (VP (ADVP (RB yet)) (VP (VBN been) (VP (ADVP (RB independently)) (VBN verified)))))))) (PERIOD .))