The Ho Chi Minh Trail was actually a labyrinth of roads, tracks and trails that stretched from North Vietnam via some strategic points, such as the Mu Gia and Ban Karai passes, into Laos and Cambodia and down into South Vietnam.  The system, known to the North Vietnamese as the Trung Son Road, was to become the subject of a massive but ultimately futile air interdiction campaign.  The trail was divided into a number of sections by the Americans in order to coordinate air operations.  The area of the Laotian panhandle that bordered North Vietnam was designated Steel Tiger and this is where the majority of missions on the Trail took place.  There were three main roads into Laos from North Vietnam and these roads twisted through mountain passes that straddled the border.  The northernmost road was designated Route 8 and came through the Keo Neua Pass; further south was Route 23 which snaked through the Mu Gia Pass; and further south still, just 20 miles northwest of the DMZ, was Route 912 which came through the Ban Karai Pass.  All these passes were very heavily defended as not only were they natural truck ‘killing zones’ for the tactical aircraft but they were also low-level routes for aircraft entering of exiting North Vietnam from the west.

The first Barrel Roll mission over the northern section of the Ho Chi Minh Trail was on 14 December 1964 when four F-105s bombed a bridge near Nape.  The first Steel Tiger mission was flown on the night of 3 April 1965 by two B-57s with the assistance of a Blind Bat C-130 flareship.  Later the Steel Tiger area was split into two sectors close to the DMZ with the northern half known as Cricket and the southern half called Tiger Hound.  The first Tiger Hound mission was flown on 6 December 1965 and the first Cricket mission on 21 January 1966.  All air strikes in the Steel Tiger area were flown under the control of an Air America, Raven or USAF forward air controllers.