seoul south korean president moon jae-in say friday north korea late launch missile japan result diplomatic economic isolation north officials say moon also warn possible new threats president moon order officials closely analyze prepare new possible north korean threats like emp electro-magnetic pulse biochemical attack moon spokesman park su-hyun tell brief north korea say early month develop hydrogen bomb carry emp attack experts disagree whether north would capability mount attack would involve set bomb atmosphere could cause major damage power grids infrastructure south korea 's moon say north korea provocations result isolation