Covert cross border infiltration plays a critical role in modern warfare. The methods counter US military technical and firepower advantages by hiding behind the international understanding about the sanctity of borders. Cross-border infiltration enables enemies to seize and maintain the offensive initiative from bases in adjacent safe haven countries. Covert cross-border infiltration allows states such as Russia to pursue aggressive geopolitical policies while maintaining plausible deniability to the international community. For non-state actors, cross border infiltration provides a survivable and practical way to achieve their political goals. This study examined how US Special Forces and First Field Forces conducted border denial operations in the Central Highland "tri-border" region during the Vietnam War. Despite the development of cross-border operations doctrine during the Vietnam War, this study concludes the US Army discarded and discounted their lessons learned. The US Army today may achieve strategic border denial by arranging tactical actions causing the adversary to suffer the cost of infiltration without gaining any benefits. Using the deep-close-support operational framework, interdiction, barrier emplacement, and a learning border security system, the US Army can disrupt enemy safe havens, neutralize infiltrators, and build capable host nation border security forces.

Approved for public release; distribution is unlimited. The opinions and conclusions expressed herein are those of the student-authors and do not necessarily represent the views of the U.S. Army Command and General Staff College or any other governmental agency. (References to these studies should include the foregoing statement.)