Which function does NOT fall under Combat Engineering?

Combat Engineering primarily focuses on tasks that support military operations in combat zones, which includes activities that enhance mobility, improve infrastructure, and provide operational capability. The functions typically associated with Combat Engineering include gap crossing, maintaining roads and trails, and the development of barriers and obstacles.

When considering which function does not fall under Combat Engineering, modifying physical environments is broader and often pertains to civilian applications as well, rather than the specific tactical focus of combat operations. Combat Engineers do make modifications to the environment but in the context of facilitating military objectives. In contrast, the other options relate directly to tasks that are integral to enabling military maneuvers and supporting tactical effectiveness. For example, gap crossing is essential for overcoming natural and man-made obstacles; maintaining roads and trails ensures supply lines and troop movements; and the development of barriers and obstacles is critical for defensive strategies.

Thus, the task of modifying physical environments lacks the specific combat application that the other options exhibit, indicating it does not strictly align with the core functions of Combat Engineering.