What is one method to delay the enemy from reaching critical facilities?

The method of using a layered application of barriers is effective in delaying an enemy from reaching critical facilities because it creates multiple lines of defense that an adversary must overcome. These barriers can include physical obstacles such as walls, fences, or security zones, as well as strategic measures like checkpoints or fortified positions. Layering these barriers can slow down the enemy's advance, disrupt their operations, and give defenders more time to respond effectively.

This approach leverages the principle of defense in depth, where multiple defensive measures are employed to create redundancy and complexity for the attacker. By requiring the enemy to navigate through several defensive layers, the chances of thwarting their progress increase significantly. This method also allows for increased opportunities for counteractions and leads to more effective allocation of resources and personnel as they can focus on critical points of vulnerability.

While other methods such as quick evacuation protocols, implementation of technology, and an increase in personnel may contribute to overall defense strategies, they do not specifically focus on physically obstructing or impeding an enemy's movement in the same direct and layered manner as barriers do.