CMS Trettinar (CHG-4) is the fourth Mergansar-class heavy cruiser built for the Caspian Navy. She acts as the lead cruiser for Task Group H, assigned to the Rautheran System along with cruisers Morselin and Picon Yar, frigates Albatross, Auklet, and Aonach, and six additional Lightning-class sloops. The flag vessel for the Task Group is the carrier Torrent.