January 1966 saw the ship taking part in local operations and making preparations for an upcoming deployment. On 7 February, she commenced a six-month cruise, arriving at Yokosuka via Midway Atoll 10 days later. Duty in the South China Sea began on 28 February with assignments as a planeguard and as a naval gunfire support ship. "Walker"'s first offensive actions of the Vietnam War occurred on 5 March in support of United States and Allied forces. This assignment was interrupted by patrol duty in the Taiwan Strait and rest and rehabilitation at Keelung, Taiwan; and Hong Kong.