1964, Tortuga operated out of Yokosuka and conducted troop and equipment lifts between Japan and Okinawa until she headed home and arrived back at San Diego on 18 December. In February 1965, the landing ship proceeded to Camp Pendleton, California, to participate in Exercise "Silver Lance," the largest peacetime landing exercise ever held. In June, she commenced a WestPac deployment. She proceeded to Buckner Bay and Da Nang and, after operating in the Orient through the early summer, returned to Long Beach in late August 1965. She subsequently conducted a lift to Okinawa before she returned to San Diego for refresher training. 1966-1967Tortuga sailed for Vietnamese waters on 1 March 1966, arrived at Vung Tau on 18 April, and relieved as support ship for Operation Game Warden — the Navy's operation designed to interdict the flow of Communist supplies along the coastlines of South Vietnam. Initially, Tortuga operated in the Rung Sat Special Zone between Saigon and Vung Tau, helping to guard the entrance to the shipping channels snaking through Viet Cong (VC) territory to the capital city.Tortuga shifted to the Mekong Delta region on 12 June to serve as a floating base for the Navy's fast PBR's of Task Force 116 and for a detachment of Army Bell UH-1B Huey helicopter gunships. Initially, the helicopters were from the 145th Aviation Detachment, however, by the end of Tortuga's tour, they were Navy aircraft from Task Force "Sea Wolf." During her support operations with the riverine assault groups, Tortuga received a number of distinguished visitors ranging from General William C. Westmoreland, Commander, Military Assistance Group; Rear Admiral Norvell G. Ward, Commander, Naval Forces Vietnam; as well as United States Ambassador to South Vietnam Henry Cabot Lodge; and news commentator Chet Huntley, who brought with him an NBC camera team to record a news story on Tortuga's river-patrol base activities. Her deployment completed in the summer of 1966, Tortuga got underway on 30 August and steamed via Japan to the west coast. She arrived at San Diego on 7 November for leave, upkeep, and overhaul. The refit lasted through April 1967, modernizing the ship and preparing her for another WestPac deployment. Following a period of refresher training and amphibious exercises, Tortuga sailed on 21 July 1967 from San Diego and arrived, via Hawaii, Guam, and the Philippines, at Da Nang on 5 September. Upon arrival, Tortuga relieved with Amphibious Ready Group "Bravo"