Which actions must a patrol leader coordinate with other units?

In a tactical environment, the coordination of the departure and re-entry of friendly lines is crucial for maintaining operational security and ensuring the safety of all units involved. This action involves detailed planning and communication between different units to avoid friendly fire incidents and to ensure that operations are synchronized. The movement of personnel across lines can directly impact the overall strategy and effectiveness of the mission, making it essential for the patrol leader to work closely with other leaders and units to ensure that everyone is informed and aligned on the timing and routes of movement.

The other options involve internal unit management. While troop discipline and individual training schedules may be important for maintaining unit cohesion and effectiveness, they typically do not necessitate coordination with other units, as they are largely managed within the unit itself. Similarly, equipment maintenance is generally a unit-specific concern and does not require the same level of coordination with other units. Thus, the departure and re-entry of friendly lines stands out as a key action that necessitates collaborative efforts across units to ensure mission success and the safety of troops.