"Hissem" remained a member of Operation "Deep Freeze" from 19 September to 28 February 1964. She then returned to the Atlantic Fleet by way of the Mediterranean, arriving 15 May. Early in 1965 "Hissem" was transferred to the Pacific Fleet. After a 5-month training period at Pearl Harbor, she sailed for Vietnam 2 September. From January 1966 to March "Hissem" was a member of TF-115 operating in the Tonkin Gulf to prevent the infiltration of supplies to the Viet Cong. On 8 March "Hissem" sailed for Pearl Harbor, where she underwent repairs and training. Once again ordered to Vietnam, "Hissem" left Hawaii 2 September and arrived Subic Bay 23 September. She resumed her previous duties and operated off Southeast Asia into 1967.