In April 1967, "Boston" returned to the Pacific for the first time in fifteen years, transiting the Panama Canal to begin a tour of combat service with the 7th Fleet. Part of Naval Gunfire Support Task Unit 77.8.9 and Sea Dragon operations off North Vietnam, she fired thousands of rounds of eight and five-inch shells against targets in North and South Vietnam. Though continuing to be based on the East Coast, the cruiser made two more deployments to the Western Pacific, in April–October 1968 and May–November 1969, the only 6th Fleet cruiser to make 3 tours to the combat zone. In May 1968, "Boston" was reclassified from "Guided-Missile Heavy Cruiser" to "Heavy Cruiser, Attack", reverting to her original hull number, CA-69. Though she retained her Terrier missiles, the swift advance of technology had made these weapons obsolete after little more than a dozen years' service, and her main battery was once again her eight-inch rifles, of which six remained in her forward turrets. On 16–17 June 1968, while conducting naval gunfire against North Vietnamese targets, in company with Australian guided missile destroyer , "Boston" was accidentally attacked by USAF jet aircraft from the 366th TFW. Two Australian sailors were killed, and minor damage occurred to both warships. The ships were in the vicinity of Swift Boats PCF-12 &amp; 19, which had come under attack by North Vietnamese helicopters. PCF-19 was sunk with 5 KIA. F-4 Phantom IIs from Da Nang Air Base responded and arrived on scene after the North Vietnamese helicopters departed. The US Navy currently maintains the Swift Boat attack as part of "Boston" and "Hobart" incident, and officially records the incident as friendly fire.