What was the primary role of the Marines during the 2nd Battle of Khe Sanh?

The primary role of the Marines during the 2nd Battle of Khe Sanh was the defense of a firebase against enemy attacks. This position was critical in the context of the Vietnam War, where Khe Sanh served as a strategic outpost near the border with North Vietnam. The Marines were tasked with holding this location against intense and sustained assaults from North Vietnamese forces.

Their defensive operations involved not only maintaining their position but also providing a secure base from which to support friendly operations in the region. The Marines utilized various tactical measures, including the establishment of strong defensive perimeters, to repel enemy forces and protect the firebase. This was pivotal because the defense was aimed at preventing the enemy from gaining a foothold that could threaten wider operations in South Vietnam.

While offensive actions and other duties were part of their overall mission during the war, the specific focus at Khe Sanh was on defense, making this the correct answer.