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USS Implicit (MSO 455)

USS IMPLICIT was one of the AGGRESSIVE - class ocean minesweepers and the second ship in the Navy to bear the name. Decommissioned on September 30, 1994, the IMPLICIT was transfered to the Taiwanese Navy the same day and recommissioned as YUNG YANG (M 1306). The IMPLICIT was stricken from the Navy list on November 29, 1994.

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Crew List:

This section contains the names of sailors who served aboard USS IMPLICIT. It is no official listing but contains the names of sailors who submitted their information.

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USS IMPLICIT History:

USS IMPLICIT was built during the major expansion and modernization of the U.S. Navy's mine countermeasures force that followed the Korean War, where naval mines had demonstrated their ability to restrict the movement of conventional warships and amphibious forces. The ship was laid down as AM 455 at Wilmington Boat Works in Wilmington, California, on October 29, 1952. Like the other ocean minesweepers of her generation, IMPLICIT was constructed with a wooden hull and extensive use of nonmagnetic materials in order to reduce the magnetic signature that could activate influence mines.

IMPLICIT was launched on August 1, 1953, sponsored by Mrs. Landon Horton. She was conducting sea trials off Southern California by January 16, 1954 and was commissioned on March 10, 1954. During the middle of 1954, she completed shakedown training in California waters and then entered a routine of mine countermeasures exercises, fleet maneuvers and training cruises off California and Mexico. On February 7, 1955, the Navy changed her classification from AM 455 to MSO 455, formally identifying her as an ocean minesweeper.

One of the earliest specifically documented fleet events of her career occurred at Long Beach on September 10, 1956, when IMPLICIT participated in a fleet review together with USS DYNAMIC (MSO 432) and the heavy cruiser USS COLUMBUS (CA 74). Long Beach was IMPLICIT's home port during the early part of her career and served as the starting point for her first western Pacific deployments.

On August 7, 1957, IMPLICIT departed Long Beach for her first deployment to the western Pacific with the U.S. Seventh Fleet. The deployment took place within the broader Cold War environment in East Asia, where the United States maintained substantial naval forces following the Korean War and amid continuing tension across the Taiwan Strait. During the cruise, IMPLICIT operated with Japanese vessels, minesweepers of the Republic of China Navy and other Seventh Fleet units. IMPLICIT returned to Long Beach on March 1, 1958.

For the remainder of 1958 and throughout 1959, she continued readiness training and mine countermeasures exercises from the U.S. West Coast. Her second western Pacific deployment began on January 8, 1960, when she again departed Long Beach. During the approximately six-month deployment, IMPLICIT participated in mine warfare exercises with Seventh Fleet forces in the Philippines and in waters off Okinawa. She completed the deployment and returned to Long Beach on July 17, 1960.

Training and mine countermeasures work continued into 1961. In August of that year, IMPLICIT participated in joint U.S.-Canadian minesweeping exercises off British Columbia. After returning to Long Beach, she began preparing for another western Pacific deployment, this time during a period when American military involvement in South Vietnam was increasing.

IMPLICIT departed Long Beach on January 2, 1962. Before beginning operations associated with South Vietnam, she participated in maneuvers conducted under the Southeast Asia Treaty Organization. She subsequently visited ports in South Vietnam, where her activities included assisting with the training of South Vietnamese naval officers and enlisted personnel. At this stage, the United States was still operating principally in an advisory role in South Vietnam, although the number of American military personnel in the country was increasing rapidly. Official Navy award records provide precise evidence of IMPLICIT's qualifying service connected with Vietnam during this deployment. She qualified for the Armed Forces Expeditionary Medal for the periods February 21 through March 7, April 26 through May 12 and June 8 through June 27, 1962. IMPLICIT completed the deployment and returned to Long Beach on August 17, 1962.

Following her return, IMPLICIT resumed fleet exercises, mine countermeasures training and underway readiness work from Long Beach. She departed again with her division on January 3, 1964 for another western Pacific deployment. The outward voyage included stops at Guam and Midway. During March, she operated off Taiwan in mine warfare exercises. IMPLICIT returned to the Taiwan Strait in May 1964 for another combined operation. During this exercise, the U.S. minesweeper operated under the direction of a Republic of China Navy division commander, providing combined U.S.-Taiwan mine warfare training in an area that remained politically sensitive throughout the Cold War. During the same western Pacific deployment, IMPLICIT also participated in another Southeast Asia Treaty Organization exercise. She returned to Long Beach on July 28, 1964.

A shipyard overhaul followed the 1964 deployment. After completion of the work, IMPLICIT resumed readiness training and tactical exercises along the California coast. The next major deployment began on September 21, 1965, when IMPLICIT departed Long Beach for the western Pacific as a unit of Mine Division 91. By this time, the war in Vietnam had expanded considerably. Large U.S. ground formations had entered combat during 1965, while the Navy had established Operation Market Time to monitor the coastline of South Vietnam and intercept vessels suspected of transporting weapons, personnel and supplies from North Vietnam to Communist forces in the south.

Although designed primarily for mine countermeasures, ocean minesweepers were among the ships assigned to the Market Time surveillance system. IMPLICIT therefore undertook coastal patrol and surveillance duties in addition to her specialized mine warfare role. These patrols included stopping, inspecting and monitoring local maritime traffic. During one patrol close to the South Vietnamese coast, IMPLICIT came under fire from Viet Cong forces ashore and returned fire with her weapons.

After a two-week stay at Kaohsiung, Taiwan, IMPLICIT departed the port on January 14, 1966 and returned to Market Time operations off Vietnam. Official Navy records document Vietnam Service Medal eligibility from January 16 through February 11, February 22 through April 4 and April 20 through June 2, 1966. The volume of maritime traffic inspected during these patrols was considerable. By March 15, 1966, IMPLICIT had participated in the boarding and inspection of more than 1,000 junks and sampans.

A more substantial combat action occurred on March 22 and March 23, 1966. Small South Vietnamese naval craft operating near the coast came under enemy fire, and IMPLICIT provided supporting fire. During the action the minesweeper fired nearly 700 rounds from her 40-mm weapon. March 22 was subsequently recognized as a qualifying date for the Combat Action Ribbon. Her service during the broader period from October 1, 1965 through June 30, 1966 was also included in a Meritorious Unit Commendation period.

IMPLICIT remained in the western Pacific into the summer. On June 28, 1966, she departed with her mine division for the United States. The homeward route took the ships through Guam, Kwajalein and Pearl Harbor before IMPLICIT arrived at Long Beach on August 2. The return to California was followed by another period of intensive training. From September 13 through September 20, 1966, IMPLICIT participated in Operation Eager Angler off Santa Rosa Island, California, conducting mine countermeasures training in home waters. She subsequently operated with a carrier task unit during a composite training exercise through December and continued local training into 1967.

During the latter part of 1967, IMPLICIT again deployed to the western Pacific. Navy records associate the ship with a Meritorious Unit Commendation period extending from September 1, 1967 through May 31, 1968. This award period establishes her participation in the activities of the cited unit but does not by itself establish that she remained continuously in Vietnamese waters throughout the entire period.

On November 29, 1967, IMPLICIT and USS PERSISTENT (MSO 491) entered Subic Bay in the Philippines at approximately 12:37 p.m. USS CONFLICT (MSO 426) had entered the harbor only minutes earlier. Subic Bay was one of the principal American logistics, repair and staging bases supporting Seventh Fleet operations in Southeast Asia.

By late January 1968, Mine Division 91 had completed approximately ten days of upkeep at Subic Bay and was preparing for what had been intended as another Market Time patrol. On January 25, the division commander decided to sail one day earlier than originally planned. The formation consisted of CONFLICT, USS ENDURANCE (MSO 435), IMPLICIT and PERSISTENT, with the division commander embarked in PERSISTENT. The planned destination was a Market Time operating area south of the Mekong Delta. The mission changed while the minesweepers were still near Luzon. Mine Division 91 was ordered to proceed to Da Nang, remove unnecessary magnetic material and prepare for an actual mine countermeasures operation. American mines had been accidentally lost in an operational area off North Vietnam and were regarded as a possible hazard to U.S. ships if they had armed after entering the water.

The diversion took place during a period of exceptional tension in the western Pacific. On January 23, 1968, North Korea had seized the U.S. intelligence collection ship USS PUEBLO (AGER 2), producing a separate crisis and a rapid concentration of American naval forces around the Korean Peninsula. Mine Division 91's assignment, however, concerned the missing mines in Vietnamese waters. The four minesweepers converged on Da Nang. CONFLICT reached the anchorage during the morning of January 29, and by late that night, all four division ships were in port. Before entering the suspected minefields, each ship had to reduce its magnetic signature as far as practical. Magnetic material not essential to the mission was landed, while equipment that had to remain aboard was positioned in accordance with magnetic-control requirements.

The timing coincided with the beginning of the Tet Offensive. Fighting ashore was audible from the ships in Da Nang during the night. On January 30, the remaining division ships refueled and completed the removal of unnecessary magnetic material. By mid-afternoon, Mine Division 91 left Da Nang in column and steamed north along the coast. During this operation the minesweepers carried temporarily mounted twin 20-mm guns. Their wooden hulls, nonmagnetic construction, magnetic-control procedures and restrictions on machinery use were intended to minimize the magnetic and acoustic signatures that could activate influence mines.

On the morning of January 31, 1968, the four minesweepers reached the first assigned minefield in the Gulf of Tonkin. They initially attempted to search the seabed by sonar, but numerous objects on the bottom produced contacts that could not readily be distinguished from mines. USS DALE (DLG 19) joined the operation to provide protection for the minesweepers. The ships then prepared their sweeping equipment and moved toward the corrected position of the first minefield. Shortly after midnight, with the minesweeping equipment streamed, Mine Division 91 began its first sweeping runs. PERSISTENT led the formation, while IMPLICIT operated as one of four ships working overlapping lanes through the suspected field.

During the operation, CONFLICT experienced a casualty involving its motor whaleboat. IMPLICIT was then following on CONFLICT's starboard quarter. She adjusted her position as directed so that CONFLICT could temporarily leave the formation and recover the damaged boat. After CONFLICT returned, PERSISTENT, ENDURANCE, IMPLICIT and CONFLICT continued repeated passes through the minefield. The division swept for approximately 24 hours and recovered its gear shortly before dawn on February 2. After a short pause, the four minesweepers began work on the second minefield at 10:15 a.m. Sweeping continued until 7:19 p.m., when the division commander determined that the two areas could be considered cleared. No mines were actuated during the sweeps. The operation therefore could not determine whether the missing mines had failed to arm, had already detonated or were no longer present in the areas being swept.

USS DALE departed the operating area at approximately 7:15 p.m. on February 2. The minesweepers subsequently returned south and anchored at Da Nang during the evening of February 4. On February 5, the division refueled and took back aboard magnetic material that had been landed before the operation.

The Gulf of Tonkin assignment was an unusual operation for the post-Korean War generation of American ocean minesweepers. Until then, most of their mine countermeasures work had been conducted in training situations or controlled exercise areas; Mine Division 91 had now operated through areas identified as actual minefields. IMPLICIT continued her western Pacific deployment after completion of the special mine clearance operation. The Meritorious Unit Commendation period associated with her service extended through May 31, 1968.

IMPLICIT returned to Vietnamese waters in 1969. Official Navy records establish Vietnam Service Medal eligibility from April 17 through June 10, 1969. Republic of Vietnam unit-citation records also include IMPLICIT during periods beginning in April and May 1969. Another Vietnam deployment followed in 1970. Official records list IMPLICIT for Vietnam Service Medal eligibility from August 29 through October 23, 1970, while Combat Action Ribbon eligibility covers August 29 through October 15. This deployment occurred during the policy of Vietnamization, under which increasing responsibility for maritime security, coastal patrol and other missions was being transferred to the Republic of Vietnam Navy. During September 1970, responsibility for the inner portion of the Market Time surveillance barrier was increasingly being assumed by South Vietnamese forces while U.S. ships continued operations farther offshore.

During the same month, mine activity became a particular concern around the Cua Viet River near the demilitarized zone. At 6:40 p.m. on September 18, 1970, USS BUCHANAN (DDG 14), positioned approximately 5,500 yards east of the mouth of the Cua Viet River, detected a small sonar contact with a strong metallic return. USS DYNAMIC, then patrolling Market Time Outer Barrier station 1B, was ordered to investigate, but its sonar was found to be inoperative. DYNAMIC was consequently directed to exchange stations with IMPLICIT, which was operating in area 7B. IMPLICIT reached the Cua Viet area on September 22 and began minehunting operations. At first light on September 23, she embarked an explosive ordnance disposal team. Divers using nonmagnetic equipment investigated sonar contacts in the approaches to the river.

The investigation did not locate the suspected mine. Items found on the bottom included pieces of angle iron, a metal locker, other debris and a case of pineapple juice. At the same time, separate South Vietnamese mine countermeasures forces were finding actual enemy mines within the Cua Viet River. IMPLICIT and the other ocean minesweepers continued searching the approaches until September 26, when the minehunting work was temporarily terminated so that they could return to Market Time Outer Barrier stations during a period of increased concern about infiltration associated with the dark phase of the moon. The ships remained positioned so they could resume mine countermeasures work in the Cua Viet area if necessary. On September 27 alone, seven separate mine incidents were reported in the Cua Viet area.

IMPLICIT's Republic of Vietnam unit-citation eligibility included October 1 through October 19, 1970, while her Vietnam Service Medal eligibility continued through October 23. Official Navy records also identify December 6, 1970 and January 1, 1971 as individual qualifying Vietnam Service Medal dates.

As American involvement in Vietnam began to decline, IMPLICIT increasingly returned to the mine warfare, readiness and training functions for which she had originally been constructed. In 1972, she was transferred to Tacoma, Washington, for service with the Naval Reserve Force and for the training of U.S. Naval Reservists. The Naval Reserve Force arrangement allowed older but still operational ships to remain available for mobilization while providing sea-going training for reserve personnel. IMPLICIT retained an active-duty cadre while reservists regularly joined the ship for training periods and exercises. Tacoma and the Pacific Northwest consequently became closely associated with the later part of her U.S. Navy career.

Photographic evidence from the later 1970s documents IMPLICIT at Pier 90 in Seattle, Washington, together with USS ESTEEM (MSO 438), USS CONQUEST (MSO 488), USS HIGBEE (DD 806), USS McKEAN (DD 784) and the repair ship USS HECTOR (AR 7).

IMPLICIT served as part of the Naval Reserve Force's mine warfare organization and was associated with Mine Division 51 at Tacoma. Navy award records show that the ship received battle-efficiency recognition for the period from January 1, 1979 through June 30, 1980.

Maintenance of an aging wooden-hulled minesweeper required regular shipyard work. Naval Sea Systems Command maintenance records show IMPLICIT undergoing a regular overhaul at Lake Union in 1982. Navy budget documentation identifies September 1982 as the completion month of this overhaul. IMPLICIT also received a Secretary of the Navy Letter of Commendation covering the period from May 24 through October 9, 1982.

By June 15, 1983, IMPLICIT was documented operating in the Gulf of Alaska while assigned to the Naval Reserve Force. Navy photography from that date shows the minesweeper underway near the Alaskan coastline during the early morning. Operations in Alaskan waters exposed reserve mine warfare crews to a very different environment from the waters of Southern California, Hawaii or the western Pacific and formed part of the training conducted by Pacific Fleet reserve units.

Another maintenance period followed in 1984. Naval Sea Systems Command records list IMPLICIT at Lake Union for a Docking Selected Restricted Availability. This was more limited than a complete regular overhaul but involved scheduled docking and maintenance intended to preserve the material condition and operational capability of the ship.

IMPLICIT returned to Alaskan waters during 1985. On July 4, she was one of seven U.S. Navy ships visiting Anchorage for Independence Day. Approximately 1,600 sailors from the visiting ships were reported in the city. The force included the nuclear-powered cruiser USS TRUXTUN (CGN 35), the frigates USS HAROLD E. HOLT (FF 1074) and USS BREWTON (FF 1086), and the ocean minesweepers USS EXCEL (MSO 439), IMPLICIT, USS ENHANCE (MSO 437) and USS GALLANT (MSO 489). The visit placed a relatively large Navy contingent in Anchorage during the Independence Day period and formed part of the continuing pattern of U.S. Navy operations and port visits in Alaskan waters.

Navy budget documents show another regular overhaul for IMPLICIT scheduled from September 1985 through February 1986. Following the overhaul, IMPLICIT continued Naval Reserve Force operations from the Pacific Northwest. She qualified for another battle-efficiency award period extending from July 1, 1986 through December 31, 1987.

Archival Navy imagery dating from 1988 documents Naval Reservists aboard IMPLICIT during a minesweeping drill. Another battle-efficiency award period extended from July 1, 1989 through December 31, 1990. IMPLICIT remained active with the Naval Reserve Force as the Cold War entered its final years. On June 6, 1990, IMPLICIT was documented at Vancouver, British Columbia. The end of the Cold War did not eliminate the requirement for mine countermeasures training. Instead, U.S. mine warfare forces continued to participate in increasingly multinational exercises, particularly in Pacific waters.

IMPLICIT participated in Rimpac 92, the large multinational Rim of the Pacific exercise centered on Hawaii and the eastern Pacific. On June 1, 1992, she was photographed at Naval Station San Diego among U.S., Australian and Canadian ships associated with the exercise. Rimpac brought naval forces from several Pacific nations together for combined maritime training, including the integration of mine countermeasures forces with larger fleet formations.

IMPLICIT remained operational into 1993. On April 14, 1993 she conducted minesweeping operations in the Strait of Juan de Fuca during Marcot '93, a joint U.S.-Canadian fleet exercise. Contemporary Navy imagery shows IMPLICIT conducting surface minesweeping while a Sikorsky MH-53E Sea Dragon helicopter of Helicopter Mine Countermeasures Squadron 15 operated nearby towing a Mark 105 hydrofoil minesweeping sled. The Strait of Juan de Fuca, between Washington State and Vancouver Island, also provided a natural setting for bilateral U.S.-Canadian maritime training.

By this point, IMPLICIT was approaching four decades of commissioned service. Newer AVENGER-class mine countermeasures ships and modern airborne and remote mine warfare systems were replacing the wooden ocean minesweepers constructed during the 1950s. IMPLICIT nevertheless remained in Naval Reserve Force service at Tacoma into 1994. On September 30, 1994, USS IMPLICIT was decommissioned after more than 40 years of service with the U.S. Navy. On the same date, she was transferred at Tacoma to the Republic of China under the Security Assistance Program. The former IMPLICIT subsequently crossed the Pacific for service with the Republic of China Navy. She arrived in Taiwan on February 5, 1995 and was formally commissioned on March 1, 1995 as YUNG YANG (MSO 1306). She was assigned to the 248th Squadron of the 192nd Fleet.

YUNG YANG was finally decommissioned by the Republic of China Navy on July 1, 2025, during a ceremony at the Hsinbin naval facility in Kaohsiung. More than 71 years had passed since USS IMPLICIT entered U.S. Navy service on March 10, 1954.

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