In order to have access to classified information in DoD, everyone is required to complete an online ‘course’ that covers the rules about security, personal devices, information sharing etc. There are also significant penalties for violations, including loss of clearance.
See https://blogs.usfcr.com/security-clearance-guide
Edit - for applicable requirements, see Part 41, Subparts 930.301 through 930.305 of Title 5, CFR, DoDD 8140.01, and DoDI 8501.