What action should be taken by a sentry if confronted with unauthorized persons at night?

When a sentry is confronted with unauthorized persons at night, the correct action is to challenge them. This is an essential protocol in maintaining security and safety around a perimeter. By issuing a challenge, the sentry clearly identifies their presence and asserts their authority in the situation.

Challenging involves asking the individuals to identify themselves and to state their purpose for being in the area. This action allows the sentry to gather information and assess the situation further. It helps to deter any potential threats, as unauthorized individuals may reconsider their intentions upon being confronted. Additionally, the sentry can gauge whether the individuals comply and if they are indeed a threat or if they may have a legitimate reason for being in the area.

Although calling for backup is a strategic option if the situation escalates, the initial step must always be to challenge the individuals present. Detaining unauthorized persons without proper authority could lead to complicating circumstances and potential violations of rights. Ignoring the individuals completely could expose the area to unauthorized access and potential harm, making the challenge the most responsible course of action.