▁miss ile ▁kill . ▁The ▁action ▁of ▁ 2 3 ▁August ▁demonstrated ▁that ▁the ▁North ▁Vietnam ese ▁Air ▁Force ▁had ▁successfully ▁executed ▁their ▁new ▁procedure , ▁which ▁was ▁helped ▁by ▁more ▁sk il ful ▁ground ▁controllers ▁who ▁directed ▁the ▁Mi G ▁f ighter ▁towards ▁their ▁targets . ▁Indeed , ▁the ▁new ▁procedure ▁gave ▁North ▁Vietnam ese ▁Mi G ▁pil ots ▁the ▁ing red ient ▁they ▁needed ▁to ▁achieve ▁a ▁kill ▁over ▁their ▁U . S . ▁oppon ents ; ▁between ▁August ▁ 1 9 6 7 ▁and ▁February ▁ 1 9 6 8 , ▁the ▁North ▁Vietnam ese ▁Air ▁Force ▁achieved ▁a ▁kill ▁ratio ▁of ▁ 1 . 1 : 1 ▁against ▁the ▁US AF , ▁with ▁the ▁loss ▁of ▁ 2 0 ▁aircraft ▁for ▁ 2 2 ▁vict ories . ▁In ▁the ▁same ▁period ▁of ▁time , ▁Operation ▁Rol ling ▁Th under ▁had ▁cost ▁the ▁United ▁States ▁approximately ▁$ 9 0 0   mill ion ▁($ 5 , 6 4 0   mill ion ▁at ▁ 2 0 1 0 ▁prices ) ▁with ▁the ▁loss ▁of ▁more ▁than ▁ 7 0 0 ▁aircraft . ▁The ▁bomb ing ▁campaign ▁continued ▁until ▁ 3 1 ▁October ▁ 1 9 6 8 , ▁when ▁it ▁was ▁abandoned ▁by ▁the ▁U . S . ▁Government . ▁ ▁Notes ▁ ▁References ▁ ▁Category : Conf lic ts ▁in ▁ 1 9 6 7 ▁Category : 1 9 6 7 ▁in ▁Vietnam ▁Category : C amp aign s ▁of ▁the ▁Vietnam ▁War ▁Category : A er ial ▁operations