(S (S (NP (NP (NP (BASENP (NNP Israel) (POS 's)) (NNS incursions)) (PP (IN into) (BASENP (JJ northern) (NNP Gaza)))) (PRN (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (VP (VBN aimed) (PP (IN at) (S (VP (VBG curbing) (NP (BASENP (NN rocket) (NNS attacks)) (PP (IN by) (BASENP (JJ Palestinian) (NNS militants))))))))))) (COMMA ,))) (VP (VBP have) (VP (VP (VBN killed) (BASENP (QP (RB over) (NN 50)) (NNS people))) (PP (IN over) (BASENP (DT the) (JJ last) (NN six) (NNS days)))))) (PERIOD .))