On 21 May, she departed Boston, initially to test the Navy's newest sonar equipment and then to proceed to her home port, Charleston, South Carolina.

During this period, she made six highly successful missile firings on the Atlantic Fleet weapon range and conducted a three-day search for an unidentified submarine contact.

Three days later, she arrived on station in the Tonkin Gulf and, on 8 June, took over positive identification radar advisory zone (PIRAZ) duties from Long Beach.

In that capacity, Wainwright maintained constant radar and visual surveillance of the gulf and adjoining coasts for the purpose of identifying all aircraft in the zone and vectoring defensive forces to the interception of any possible airborne enemy intruders.

Since her duties afforded her a continual picture of the events occurring in the air over the zone, she also served as a base for search and rescue (SAR) helicopters.

On 14 September, she turned PIRAZ duties back over to Sterett and steamed off for a month of port visits which included a brief upkeep period at Subic Bay followed by calls at Hong Kong and Yokosuka.

Back on station on 28 November, Wainwright concluded the year as the Navy's air coordinator in the northern portion of the Tonkin Gulf.

The warship spent the first three days of 1969 winding up her third and final tour of duty as PIRAZ ship and then set a course for the Philippines, the first pause on her way home.

For the first two weeks of June, Wainwright remained in the West Indies and participated in the NATO anti-submarine warfare exercise, "Spark Plug", along with ships of the navies of Canada, Great Britain, the Netherlands, and Portugal.

After three days in Charleston, Wainwright got underway for gunnery and missile shoots on the Atlantic Fleet weapons range near Puerto Rico.

On 25 August, the guided missile destroyer stood out of Charleston, bound for her third and final deployment to the western Pacific in conjunction with the Vietnam War.

On 20 November, she relieved Jouett on PIRAZ station and took up familiar duty as the American air coordinator in the northern part of the gulf.

For almost a month, she alternated between north and south SAR stations, taking time briefly in mid-December to participate in Operation "Beacon Tower", a three-day exercise to test the readiness of American warships in the Tonkin Gulf to meet and deal with air and surface attacks.

After a final two-day stop at Subic Bay, Wainwright began the long voyage back to Charleston which took her through the Indian Ocean, around the Cape of Good Hope, and across the southern Atlantic to complete her first circumnavigation of the globe.

Those modifications were completed by mid-July, and Wainwright occupied the following four months with operations along the eastern seaboard in conjunction with the initial evaluation of her LAMPS helicopter.

During ASW exercises in Greek waters, Wainwright contacted, tracked, and positively identified four Soviet submarines in spite of their strenuous efforts to evade.

On 17 February, she departed Genoa in company with the Italian cruiser Vittorio Veneto to participate in National Week XV, a multinational naval exercise of broad scope conducted across the Central Mediterranean.

After National Week XV, Wainwright punctuated a series of Sixth Fleet ASW and AAW exercises with visits to many of the ports already mentioned as well as at Athens, Civitavecchia, Livorno, and Golfe Juan.

That same day, she departed Rota for Lisbon, where she joined Guam and Bowen in preparation for a transatlantic exercise to test the concept of the sea control ship.

For the remainder of the year, the warship was busy with refresher training, a myriad of tests, qualifications, inspections, and evaluations, and other normal Second Fleet operations conducted along the southern Atlantic coast and in the Caribbean.

En route to the Mediterranean, the guided missile destroyer joined Forrestal and Tunny in a series of ASW, surface, and air action drills, at the conclusion of which Wainwright continued on her way to Spain.

On 6 July, the ship departed New York and headed back to Charleston to resume her more mundane schedule of special operations and training cruises.

January 1978 was spent in grooming for a multi-threat training exercise, "READEX 1-78", which took place in February in the southern Florida and Caribbean operating areas.

The 14 April mining nearly sank the guided missile frigate USS Samuel B. Roberts, which was sailing in the Persian Gulf as part of Operation Earnest Will, the 1987-88 convoy missions in which U.S. warships escorted reflagged Kuwaiti oil tankers to protect them from Iranian attacks.

By the time Roberts was towed to Dubai on 15 April, battered but saved with no loss of life, U.S. planning for the retaliatory operation had already begun in Washington and in the Middle East.

The attack by the U.S. helped pressure Iran to agree to a ceasefire with Iraq later that summer, ending the eight-year conflict between the Persian Gulf neighbors.

Fighting continued when the Iranian frigate Sahand departed Bandar Abbas and challenged elements of an American surface group.

The Cobra, attached to USS Trenton, was flying reconnaissance from Wainwright and crashed sometime after dark about 15 miles (24 km) southwest of Abu Musa island.

On 6 November 2003, the International Court of Justice dismissed Iran's claim for reparation against the United States for breach of the 1955 Treaty of Amity between the two countries.

The Court also ruled that it, "...cannot however uphold the submission of the Islamic Republic of Iran that those actions constitute a breach of the obligations of the United States of America under Article X, paragraph 1, of that Treaty, regarding freedom of commerce between the territories of the parties, and that, accordingly, the claim of the Islamic Republic of Iran for reparation also cannot be upheld;" Wainwright was decommissioned on 10 November 1993 and was mothballed for most of a decade.