Recommissioned on 15 October 1966 at Mare Island Naval Shipyard with Lieutenant James C. Kunz USN in command. Garrett County saw extensive service during the Vietnam War, operating as part of Operation Game Warden, a brown-water navy effort to keep the rivers free of Viet Cong infiltration. Four LST were recommissioned to support river patrol operations with the intent of keeping three ships on-station at any one time supporting a River Division of 10 Patrol Boat, River, a Detachment of 2 UH-1 Helicopter Gunships and a SEAL Platoon. The ship not on-station was undergoing ship repairs in the Western Pacific. "Garrett County" reported on-station to CTF 116 on 12 March 1967 and operated as a Patrol Craft Tender (AGP) for the next 48 months on the rivers of the Mekong Delta.