United States Naval Ship (USNS) is the prefix designation given to non-commissioned ships that are property of the United States Navy (USN).
[1] United States Naval Ships are unarmed auxiliary support vessels owned by the U.S. Navy and operated in non-commissioned service by Military Sealift Command with a civilian crew.
Some ships include a small military complement to carry out communication and special mission functions, or for force protection.
Additionally, the United States Naval Ships hull classification symbol begins with "T-" to denote its civilian crew.
The USNS prefix can be assigned only while the ship is owned by the U.S. Navy.