NEW : China says sanctions over the last eight years only caused it to bolster its nuclear deterrent . U.N. voted unanimously to approve new measures . North Korea calls for all parties to calm down but stands behind new The U.N. Security Council sanctions . Questions over sanctions ' effectiveness . North Korea responds with a fresh statement of angry threats .
NEW : China says sanctions over the last eight years only caused it to bolster its nuclear deterrent . U.N. voted unanimously to approve new measures . North Korea calls for all parties to calm down but stands behind new The U.N. Security Council sanctions . North Korea responds with a fresh statement of angry threats .