World leaders expressed concern on Thursday that North Korea will quit six-party nuclear disarmament talks and will  bolster its nuclear weapons arsenal.
North Korea wants to improve their nuclear weapons
North Korea will quit six-party nuclear disarmament talks and will bolster its nuclear weapons arsenal.
( z1 want :ARG0 ( z2 country :name ( z3 name :op "North" :op "Korea" ) ) :ARG1 ( z4 improve :ARG0 z2 :ARG1 ( z5 weapon :mod ( z6 nucleus ) :poss z2 ) ) )