China Unveils New Baseline for Territorial Waters in Gulf of Tonkin

Joaquin Camarena
Joaquin Camarena
Joaquin completed his undergraduate and graduate education at a Texas university and has studied extensively in China. As a former Marine Corps intelligence analyst, he worked in the Indo-Pacific region. His areas of expertise include PLA modernization, particularly PLAN/PLANMC and its expeditionary capabilities, as well as CCP and Chinese domestic politics. He also runs the Sino Talk brand on Instagram and Twitter and is the IndoPacific Desk Chief for Atlas.

More From Me

Baseline Announcement

On March 1st, the Department of Boundary and Ocean Affairs, under China’s Foreign Ministry, released a statement on its website and Chinese social media accounts that outlined China’s new baseline in the Beibu Gulf. The statement contained six coordinate points that declared “the baseline of the territorial sea in the northern part” of the Beibu Gulf, also known as the Gulf of Tonkin.

China’s new baseline created from points outlined in China’s Foreign Affairs Statement (Source: China Ministry of Foreign Affairs/Google Earth)

The Department also released an explainer on its WeChat account on the same day as the statement, which answered four questions regarding the new baseline. The first question explained territorial baselines by quoting the United Nations Convention on the Law of the Sea (UNCLOS) definition. The answer also explains the two methods, normal or straight baseline, countries can utilize to draw them. It is also said that coastal countries can use a hybrid form that combines both methods to better adapt the territorial sea baselines to their countries. The answer then explains that the 1992 Law of the People’s Republic of China on Territorial Sea and Contiguous Zone specifies that the country will use the straight baseline method to delineate its territorial sea.

The second question discussed the reasons why China announced the baseline for the territorial sea. The first reason that China said the announcement was necessary for China to exercise its jurisdiction and national sovereignty. The second reason is due to the “internal waters, territorial seas, and Exclusive Economic Zones having different management regulations and use plans.” They said the delineation of baselines will both clarify and provide a basis for the standardized and scientific use of the waters by provinces and regions.

English translation of Statement of the Government of the People’s Republic of China on the Baselines of the Territorial Sea Adjacent to the Northern Part of Beibu Gulf

The answer also provided previous examples of when China made changes to the baselines of its territorial waters, including the 1996 and 2012 revisions that modified the baselines to include the Paracels and Diaoyu Island chains. They then said the announcement of the new baseline in the Beibu/Tonkin Gulf is an important part of China improving its delineation of territorial sea baselines. However, it also stated that the baseline will assist in the economic development of Guangdong and Hainan Provinces and the Guanxi Autonomous Region and accomplish the “strategic goal” of developing China into a maritime power.

The explainer also provided the legal basis for China changing the baseline, saying that it “strictly complies” with bilateral agreements and domestic and international laws. Regarding domestic laws, the answer said that the changes are in accordance with the Law of the People’s Republic of China on Territorial Sea and Contiguous Zone. The answer also referenced the United Nations Convention on the Law of the Sea as part of its answer regarding international laws. The Department also highlighted the 2000 bilateral agreement signed between the two countries, called the China-Vietnam Delimitation Agreement on the Territorial Sea, Exclusive Economic Zone, and Continental Shelf of the Two Countries in the Gulf of Tonkin.

The answer then explained that included in the six base points, Junbi Jiao is a base point that was announced in the 1996 revision. Furthermore, the base point, called the First Point of the China-Vietnam Beibu/Tonkin Gulf Demarcation Line, is based on the China-Vietnam Beibu Guld Delimitation Agreement. The answer then explained that China selected the five points from the various coastal prominences and islands on the northern outer edge of the gulf according to UNCLOS’ terms.

The final answer explained the various impacts that the announcement of the new territorial sea baseline would have on the surrounding area. It first pointed out that the Beibu Gulf only involves two coastal countries, China and Vietnam, and that they delimited the boundaries of the gulf in 2000. It then said that the new baseline is on China’s side of the gulf and will not affect Vietnam’s rights and interests, or “let alone any third country’s rights and interests.” However, the new baseline, it points out, will “clarify the nature of waters” in the northern waters of the Beibu/Tonkin Gulf. Furthermore, the clarification will help China “expand and deepen international maritime cooperation with relevant countries” and assist in the development of global maritime initiatives.

Vietnam’s Reaction

Vietnam’s reaction was muted and consisted of only a statement the Foreign Affairs Ministry Spokesperson, Pham Thu Hang, gave to a question during the March 14th daily press conference and one English-language article by one Vietnamese news outlet.

In the statement, Pham said that both Vietnam and China are the “sole states bordering the Gulf of Tonkin” and that both countries signed the agreement on delimiting the gulf in 2000, which came into force in 2004. She then presented Vietnam’s view regarding China’s new baseline for territorial waters, which is that “coastal States are obligated to comply” with UNCLOS in developing their baselines for measuring the breadth of the territorial sea and ensure that the baselines do not adversely “affect the legitimate rights and interests of other States.” Pham then explained that these rights include “the freedom of navigation and the transit of passage through straits used for international navigation in accordance” with UNCLOS.

Statement from Vietnam’s Foreign Affairs Ministry about China’s new baselines (Photo: Vietnam Foreign Affairs Ministry)

The spokesperson then said that Vietnam informed China of its views on the new baselines and “will continue to do so in the spirit of friendship, understanding, and mutual respect.” She then said that the country urges China to both respect and comply fully with the 2000 Agreement and the UNCLOS. Furthermore, the spokesperson also said Vietnam reserves the legal interests and rights afforded to it under international law. Pham then said Vietnam still has the same position it expressed in its 1996 Statement regarding the 1996 declaration made by China concerning the requirements for “measuring the breadth of China’s territorial sea.”

The March 14th English-language article about Vietnam’s reaction to China changing the baselines consisted of reiterating the statement Pham made. Furthermore, the article also pointed out that the six points are not among the 49 base points China announced in 1996 to measure its territorial seas. However, the article’s writers did not criticize or question China’s announcement or the country’s rationale for the new baseline in the Gulf of Tonkin.


China’s announcement of the new baseline in the Gulf of Tonkin is likely a response to not having any base points in the area previously. For example, Junbi Jiao is the 49th and last base point that China released in 1996 to delineate its territorial seas. There are no base points beyond Junbi or in the surrounding area on any publicly available maps that delineate China’s territorial seas in the northern part of the Beibu Gulf. Furthermore, China’s ‘reasons’ as outlined in the explainer are relatively benign since they are legitimate under both international law and the 2000 bilateral agreement signed between Vietnam and China.

The reasons China gave involve increasing the economic development of both the Guangxi Autonomous Region and Hainan Province, which will enable the country to develop into a maritime power. However, China’s announcement does come as the country continues to press its claims against Vietnam in the South China Sea (SCS), especially in the area surrounding Vanguard Bank. The new base points could enable it to force Vietnam to renegotiate the 2000 Agreement or potentially negotiate over Vanguard Bank and the oil and natural gas fields. For example, China uses the baselines to extend its territorial waters and contiguous zone 24 nautical miles (45 km) deeper into the gulf. The extended zones would infringe on Vietnam’s territorial waters, especially along the area of the border it shares with China.

Furthermore, the zones would likely negatively affect the port of Haiphong, which is Vietnam’s second largest port in terms of deadweight tonnage handled. While China did outline how the new baseline is compliant with both international laws, specifically UNCLOS and the 2000 bilateral agreement, the country does have a history of ignoring laws if they do not benefit or favor them. The most notable example is UNCLOS and how China routinely ignores it through its actions against not only Vietnam but other countries in the SCS, such as the Philippines.

China also included wording in the explainer, saying that the delineation issue in the Gulf of Tonkin is only the concern of it and Vietnam. The country included the wording to signal to third party countries, such as the United States, not to get involved in any dispute that could occur due to the new baseline. The reason why is due to the potential for the United States to assist Vietnam in a similar matter as it does with the Philippines in the SCS. Furthermore, the United States could also conduct Freedom of Navigation (FoN) operations in the Gulf of Tonkin to show that the country does not recognize any new Chinese claims.

However, the United States would likely be hesitant to conduct FoN operations in the Gulf of Tonkin since it is so close to the Chinese coast. They would also view any FoN operations as doing little, if anything, to dissuade China from continuing to press the new baseline. Vietnam would also be hesitant to ask the United States or other countries for assistance or even raise the issue to prevent China from using economic coercion against the country.