period was highlighted by 33 days of services on Yankee Station, including participation in the Southeast Asia Treaty Organization (SEATO) exercise Sea Spirit with units of the U.S. Navy, Royal Australian Navy, Royal New Zealand Navy, British Royal Navy, Philippine Navy, and Royal Thai Navy. She also provided services for the Seventh Fleet off the coast of Vietnam. On 1 July 1969, Bugara was reclassified as an auxiliary submarine with the new hull classification symbol AGSS-331 for the period she served on Yankee Station. On 20 July 1969, Bugara receuved orders to proceed to Yokosuka, Japan, and then to San Diego, where she arrived on 4 August 1969. From 5 August to 14 November 1969, she participated in Fleet Exercise StrikeEx 4-69 and provided services to various units of the U.S. First Fleet. On 1 October, her hull classification symbol reverted to SS-331'''. On 2 October 1969, she departed San Diego for the Puget Sound area to render services to the submarine . While in the vicinity, she also provided assistance to Canadian air and surface units from 7 to 9 October 1969.Bugara entered the Mare Island Naval Shipyard on 14 November 1969 and celebrated her 25th anniversary of commissioning on 15 November while preparing for interim drydocking. At the shipyard, she accomplished a battery renewal that was completed on 3 December 1969. She then returned to San Diego for Christmas holiday leave and upkeep. Decommissioning During 1970, the U.S. Navy deemed the five remaining Fleet Snorkel submarines — Bugara, , , , and — "far below the standards of a Guppy III submarine" and prohibitively expensive to modernize. The Board of Inspection and Survey found Bugara unfit for further naval service and recommended she be stricken from the Naval Vessel Register.Bugara was decommissioned on 1 October 1970 and stricken from the Naval Vessel Register the same day. She was transferred from the custody of Commander, Submarine Group, San Francisco Bay Area, to that of Commanding Officer, Inactive Ship Facility, Mare Island Naval Shipyard. She was selected for sinking as a target along with the decommissioned attack cargo ships and in tests of the Mark 48 torpedo off the coast of Washington. The testing schedule originally called for the submarine to sink Bugara sometime during the week of 23 May 1971, but at the beginning of June 1971 the test had not yet been carried out and Bugara remained afloat.