Vietnam Condemns Chinese Research Vessel’s Presence in Gulf of Tonkin

On June 6th, Vietnam’s Ministry of Foreign Affairs (MOFA) spokesperson, Pham Thu Hang, issued some comments about the Hai Yang 26 survey ship that was conducting a survey in Vietnam’s Exclusive Economic Zone (EEZ) near the Gulf of Tonkin. Hang made the comments in response to a question a reporter from a Vietnamese news outlet asked during the MOFA’s 10th regular press conference. The Chinese survey vessel has reportedly been operating in the area of China’s Hainan Island since late May. However, the Hai Yang’s present location cannot be verified because the vessel has not activated its AIS (Automatic Identification System) tracker.

Ministry of Foreign Affairs Statement

Hang’s statement about the survey ship was a response to a reporter’s question: “there is information about the Hai Yang 26 vessel conducting surveys in Vietnamese waters outside the mouth of the Gulf of Tonkin. Please, what is the Spokesperson for Vietnam’s response?” Hang said that the People’s Liberation Army Navy’s (PLAN) Hai Yang 26 survey vessel is conducting an illegal survey in Vietnamese waters, and that the country has communicated with China several times regarding this issue. The spokesperson said Vietnam is “very concerned” and requests that China immediately stop the illegal survey of the country’s EEZ and continental shelf, which was “established in accordance with the United Nations Conventions on the Law of the Sea (UNCLOS).”

Vietnam’s Ministry of Foreign Affairs statement to question asked about Hai Yang 26 survey in the Gulf of Tonkin

Hang then urged China not to conduct similar illegal activities, “fully respect Vietnam’s sovereignty and jurisdiction, respect international law, and comply with UNCLOS” and the Declaration of Conduct of Parties in the South China Sea. She said China should “seriously implement the common awareness” that the two leaders agreed to better control and resolve sea disputes. The spokesperson then said that China should maintain the momentum of bilateral relations, make a positive contribution, and take responsibility for peace and stability in the South China Sea.

Hai Yang 26 Survey Ship CS Chen Jinglun

The Hai Yang 26 is a Type 636A/Shupang class hydrologic survey vessel that is a successor to the Type 636 class, of which only one was built. The class consists of nine vessels named after notable Chinese mathematicians, physicists, and scientists. The vessels can conduct various bathymetric surveys, such as gathering seabed geomorphological measurements, seabed surface geological exploration, ocean density surveys, measurement of ocean temperature and salinity, and tide detection. The ships can also gather meteorological observations and place military buoys. The Type 636As adopted noise elimination measures to reduce the ship’s noise while increasing its efficiency. The measures include large-slash propellers, a multi-faceted shock absorption system incorporating raft shock and block devices, soft rubber connections to connect equipment, and a new ultrasonic energy generator to convert electrical power to mechanical power.

An undated photo of Haiyang 26/the CS Chen Jinglun near a pier with a delegation viewing the vessel.

The vessel is approximately 242 feet (129 meters) long, has a beam of 56 feet (17 meters), and has a full displacement of about 6000 tons. The Type 636A’s endurance is approximately 15,000 nautical miles (28,000 kilometers) at 15 knots (28 kph), and it can travel 3,500 nautical miles (6500 kilometers) before requiring replenishment. The vessel has a single ship structure and a tilted bow to increase deck area and reduce the impacts of upper waves. The superstructure is located in the middle of the vessel to increase volume and improve the measurement capabilities of the ship. The ship also has a wide helipad at the stern, so helicopters can take off and land. The Type 636A is equipped with approximately 20 measurement systems. The vessel can conduct survey and measurement operations under Level 5 sea conditions and can safely sail in any sea type except the polar and ice areas under Level 9 sea conditions. The ship can operate in areas with a maximum wind resistance of Level 12. The Type 636A can still carry out water depth measurements in areas up to 100 nautical miles (185 kilometers) from the shore.


The Hai Yang 26’s survey mission in Vietnam’s EEZ is to collect hydrologic data for the area around southern Hainan Island and the Gulf of Tonkin to develop charts for its Type 094/Jin class nuclear submarine fleet. The vessel’s survey mission is a continuation of China’s patrols in Vietnam’s EEZ to normalize its presence and force Vietnam to negotiate over its claims in the South China Sea (SCS). The PLAN conducted the hydrologic survey to develop charts for use by its Type 094 submarines stationed at the Longpo Naval Base. The charts would allow for the Type 094s to move through the Gulf of Tonkin and into the SCS more efficiently and safely to conduct their deterrence missions. Furthermore, the submarines would also use the charts to find undersea terrain that would obstruct or hide their sonar signature. The aircraft carriers and other PLAN vessels could also use the charts for navigational purposes and to develop a better understanding of the undersea terrain to counter any enemy submarines.

China will also use the Type 636A’s mission in the Gulf of Tonkin to force Vietnam to negotiate over its claims in the SCS by normalizing its presence in the country’s EEZ. The Hai Yang 26 is not the first time that China has sent research vessels to conduct surveys in Vietnamese waters. These patrols are usually conducted around Vanguard Bank and the surrounding natural gas fields because the fields push against China’s red lines for the SCS. The survey missions fit into China’s larger strategy, which uses gray zone tactics to push Vietnam into bilateral negotiations over the SCS and force the countries to back down from their claims.

For example, China understands that Vietnam would be hesitant to publicly condemn the country’s intrusion patrols into Vietnam’s EZZ because of the potential for anti-China protests to occur. Furthermore, Vietnam would also be hesitant to react strongly to the patrols since China could use economic coercion to stop the country from condemning the patrols. China could increase its patrols around the natural gas fields that surround Vanguard Bank to stop or disrupt production at the sites. The natural gas disruptions would increase pressure on the country’s already-strained electricity grid, which would lead to blackouts or lowered electricity production.

Joaquin Camarena
Joaquin Camarena
Joaquin the panda began Sino Talk in 2022 primarily to give an objective, unbiased view on China related topics as well as other issues related to the Indo-Pacific region. He spent several years studying and traveling throughout China and many countries in the Indo-Pacific region. In another life, the panda was also a U.S. Marine intelligence analyst who enjoyed bamboo MREs and drinking bourbon and soju. Indo-Pacific Division Desk Chief for Atlas News.


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