"Carpenter" departed Hawaii on 27 December, and after a short stop to refuel at Subic Bay, joined TG 77.4 for carrier screening operations on 12 January 1966. After six weeks of plane-guard duty, "Carpenter" shifted to the search and rescue station in the Gulf of Tonkin in early March. On 20 March, the destroyer began a two-day surveillance mission of the Communist Chinese-held Paracel Islands before returning to Yokosuka on the 26th. "Carpenter" returned to the Gulf of Tonkin in mid-April for a few days of patrol and screen duties before she steamed to the gun line off the coast of Vietnam on 21 April. Over the next week, she fired a total of 318 5-inch rounds at enemy caves and bunkers in support of the United States Army amphibious landing in Operation AUSTIN II. Following visits to Subic Bay and Hong Kong, the warship returned to Hawaii, arriving there on 11 June.