What strategic role do 'obstacles' play in military operations?

Obstacles play a pivotal strategic role in military operations primarily by serving as barriers to control enemy movement. By effectively placing obstacles, military commanders can influence the enemy's ability to maneuver, thereby shaping the battlefield. This strategic utilization can slow down or divert enemy forces, making them more vulnerable to defensive actions or counterattacks. Additionally, obstacles can help to create chokepoints, which can be advantageous for defending troops who can concentrate their forces against a smaller number of attacking units.

The other options, while relevant to broader tactical considerations, do not encapsulate the primary strategic role of obstacles. Providing cover for troops is more about concealment rather than control of movement. Supply storage is essential for operational sustainability but does not relate directly to the concept of obstacles in military strategy. Vehicle maintenance is necessary for operational readiness but is not a function of obstacles on the battlefield. Therefore, the definition of obstacles as barriers for controlling enemy movement is crucial in understanding their strategic importance in military tactics.