Fleet liaison officer

From Memory Alpha, the free Star Trek reference.

A fleet liaison officer is usually a foreign spokesperson who represents the interests of his or her home government's fleet.

During the Dominion War, Lieutenant Commander Worf served as Starfleet's fleet liaison officer to the Klingon fleet. In 2373, circumstances forced Captain Benjamin Sisko to relieve Worf of his Starfleet duties. As a result, Jadzia Dax was assigned as fleet liaison officer due to her experience with Klingon culture. (DS9: "Soldiers of the Empire")