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 has been increasing its nuclear weapons arsenal.
( z1 increase :ARG0 ( z2 country :name ( z3 name :op "North" :op "Korea" ) ) :ARG1 ( z4 arsenal :cxnsistof ( z5 weapon :mod ( z6 nucleus ) ) :poss z2 ) )