▁was ▁to ▁persu ade ▁the ▁North ▁Vietnam ese ▁Government ▁to ▁find ▁a ▁comprom ise ▁through ▁negoti ations . ▁Origin ally ▁the ▁U . S . ▁J oint ▁Chief s ▁of ▁Staff ▁submitted ▁a ▁list ▁of ▁ 9 4 ▁targets ▁to ▁be ▁hit ▁over ▁a ▁period ▁of ▁ 1 6 ▁days , ▁but ▁U . S . ▁President ▁Ly nd on ▁Johnson ▁decided ▁to ▁include ▁military ▁targets ▁in ▁order ▁to ▁gradually ▁apply ▁pressure ▁on ▁the ▁North ▁Vietnam ese ▁Government , ▁so ▁the ▁list ▁of ▁targets ▁grew ▁to ▁ 4 2 7 ▁by ▁the ▁end ▁of ▁the ▁campaign . ▁In ▁the ▁first ▁phase ▁of ▁the ▁operation , ▁which ▁last ed ▁from ▁spring ▁to ▁summer ▁of ▁ 1 9 6 5 , ▁American ▁air power ▁mainly ▁target ed ▁the ▁North ▁Vietnam ese ▁capital ▁of ▁H ano i ▁and ▁its ▁limited ▁industrial ▁base . ▁ ▁However , ▁by ▁the ▁end ▁of ▁the ▁year , ▁the ▁United ▁States ▁had ▁failed ▁to ▁achieve ▁the ▁object ives ▁of ▁Rol ling ▁Th under , ▁because ▁North ▁Vietnam ▁continued ▁to ▁send ▁its ▁troops ▁and ▁military ▁supplies ▁down ▁the ▁Ho ▁Chi ▁Min h ▁Tra il , ▁which ▁demonstrated ▁that ▁the ▁North ▁Vietnam ese ▁Government ▁was ▁not ▁ready ▁to ▁quit ▁the ▁war . ▁In ▁response ▁to ▁domestic ▁political ▁pressure ▁to ▁do ▁more , ▁President ▁Johnson ▁shift ed ▁priority ▁of ▁the ▁campaign ▁to ▁inter diction . ▁From ▁summer ▁ 1 9 6 5 ▁to ▁the ▁winter ▁period ▁of ▁ 1 9 6 6 – 6 7 , ▁the ▁campaign ▁was ▁aim ed ▁at ▁de grad