Which regulation discusses the security of unclassified Army property?

The regulation that discusses the security of unclassified Army property is AR 190-51. This regulation establishes the policies and procedures for safeguarding unclassified Army property and provides guidelines on how to effectively protect this property from theft, loss, or misuse. It focuses on ensuring that all personnel involved have a clear understanding of their responsibilities in maintaining the security of such assets.

In the context of the other options, AR 710-2 pertains to the supply policy for property accountability, primarily focusing on the management and maintenance of Army supplies and equipment. AR 30-22 addresses the management of Army food service programs, while AR 190-11 deals with physical security of sensitive and classified property. Therefore, AR 190-51 is specifically aligned with the security protocols related to unclassified Army property, making it the correct choice for the question presented.