MP may be tasked to visually inspect both incoming and outgoing mail at local Army post offices for customs violations. MP may be aided by military narcotics or explosives detector dogs in performing these customs inspections. Mail containing narcotics, explosives, or other contraband is processed in accordance with directives issued by Department of the Army. MP may be required to operate control posts and border patrols and to supervise crossing points at international borders.
Many countries control the movement of military personnel and civilians at their borders.
Border control is maintained for reasons of security, customs and tariff enforcement, protection of the civilian economy, and apprehension of criminals, absentees, and persons of intelligence interest. Control is maintained through the establishment of authorized road or rail crossing points, border patrols, control posts, and, if feasible, liaison with authorities of neighboring countries. Prohibited or restricted zones are often used to help control circulation at borders. In border control, MP normally coordinate with host country police, counterintelligence units, and civil affairs units. Border control posts and patrols are also furnished border alarms.