What designation do ships operated by the Military Sealift Command carry?

Ships operated by the Military Sealift Command (MSC) carry the designation USNS, which stands for United States Naval Ship. This designation is used for non-combatant ships that are primarily involved in logistical support for the U.S. Navy. The use of USNS indicates that these vessels are part of the naval service and are utilized to transport supplies, fuel, equipment, and personnel.

In contrast, USS (United States Ship) is reserved exclusively for commissioned ships of the United States Navy, which are operational and typically involved in military combat. Meanwhile, USN is an abbreviation for United States Navy itself, and USAF stands for United States Air Force, neither of which are applicable to the designations of ships operated by the Military Sealift Command. Therefore, USNS is the correct designation and reflects the unique operational role these vessels play in supporting naval missions without being combatant vessels themselves.