What AR provided guidance for handling sensitive unclassified material?

The Army Regulation (AR) that provides guidance for handling sensitive unclassified material is AR 380-5, titled "Army Information Security Program." This regulation outlines the policies and procedures for the protection of sensitive information, including unclassified material that requires safeguarding due to its potential impact on national security or other interests. It emphasizes the need for proper classification, marking, and handling to prevent unauthorized access or disclosure.