The following is the July 28, 2021 memo from Deputy Defense Secretary Kathleen H. Hicks updating the guidelines from the Department of Defense on wearing masks.
From the memo
MEMORANDUM FOR SENIOR PENTAGON LEADERSHIP
COMMANDERS OF THE COMBATANT COMMANDS
DEFENSE AGENCY AND DOD FIELD ACTIVITY DIRECTORS
SUBJECT: Updated Mask Guidance for all DoD installations and Other Facilities
Reference: Deputy Secretary of Defense Memorandum “Updated Mask Guidelines for Vaccinated Persons,” May 13, 2021