From where does the sentry derive their authority?

The authority of a sentry primarily derives from the established framework of military regulations, which includes the US Navy Regulations. These regulations define the roles, responsibilities, and expectations for service members, including sentries, providing them with the legitimate authority to perform their duties. The US Navy Regulations detail the conduct required for personnel while on duty and outline the expectations for maintaining security and following lawful orders. This authority empowers the sentry to enforce rules and react to threats effectively, as it is grounded in formalized military structure and discipline.

Other options, while relevant in a broader sense, do not specifically empower sentries in the same foundational manner. For instance, Department of Defense directives and orders from the Commanding Officer may inform or affect the actions of a sentry, but the regulations provide the overarching policy and legal basis for the duties and authority a sentry holds. The military code of conduct primarily outlines ethical behavior and standards rather than explicit operational authority.