The "Triangulation" order in Call of Duty: Modern Warfare 4's DMZ mode, part of the "Underground" chapter, requires players to place a transmitter on two radio towers. Despite the mission's phrasing, a specific transmitter item is not needed to complete this objective.
To begin, deploy into the Hajin area and consult your in-game map. When the "Triangulation" objective is active, all radio towers will be clearly marked with orange icons. The map will display the locations of these towers, including those designated as lieutenant towers.
Once you reach a radio tower, the next step is to ascend to its summit. Upon reaching the top, look for a prompt that will allow you to place a radio transmitter. This interaction point is typically found on one of the metal poles that form the tower's structure. Perform this action at two separate radio towers to fulfill the mission's requirements.
Following the completion of this task, players must then proceed to the top of La Grand Vie, a named location situated in the Songdo Wharf area to the east of Hajin, and repeat the transmitter placement process. This will finalize the objective.
For players seeking further assistance, guides are available on increasing stash size, locating a dynamic op phone, and acquiring electronic sensors within DMZ.