"strongpoint obstacle system" . . "U.S. strategic failure" . . . "22pxDemocratic Republic of Vietnam(North Vietnam)" . . "McNamara Line electronic barrier" . . "22pxUnited States" . "McNamara Line#Cover name changes" . . . "McNamara Line's electronic barrier" . "Strongpoint Obstacle System" . . . . "McNamara Line" . . . . "McNamara Line" .