Final answer:
Search progress reports for Duty Status Whereabouts Unknown (DUSTWUN) casualties are required every 12 hours to coordinate search and rescue operations effectively.
Step-by-step explanation:
The frequency at which Duty Status Whereabouts Unknown (DUSTWUN) casualties require search progress reports is every 12 hours. DUSTWUN is a classification used by the military for personnel whose status is uncertain and who may be missing. It indicates that an individual cannot be located but is not confirmed dead. Quick and consistent updates are crucial in order to provide the needed information to commanding officers and support units involved in the search and rescue operations. Efficient communication and reporting are essential in these situations for coordinating efforts and resources to facilitate the successful location and recovery of the individual.