5-62. Zone reconnaissance is a form of reconnaissance that involves a directed effort to obtain detailed information on all routes, obstacles, terrain, and enemy forces within a zone defined by boundaries (ADRP 3-90). Obstacles include existing, reinforcing, and areas with CBRN contamination. Commanders assign a zone reconnaissance mission when they need additional information on a zone before committing other forces. It is appropriate when the enemy situation is vague, existing knowledge of the terrain is limited, or combat operations have altered the terrain. A zone reconnaissance may include several route or area reconnaissance missions assigned to subordinate units.