Are China and Vietnam on collision course over Beijing's 'creeping' demarcation in Gulf of Tonkin?

Vietnam's inaction to China's demarcation of its territory in the Gulf of Tonkin where the two countries have unresolved maritime boundaries could be a sign of Hanoi's desire to discuss the issue behind closed doors.

Analysts say China's move may not comply with international maritime conventions, adding that Beijing's "creeping" encroachment shows that it is aiming to assert greater control over an important body of water.

On March 1, Beijing released a statement showing a set of seven base points that, when connected, form the baseline for its territorial claims in the Gulf of Tonkin, known as Beibu Gulf in China.

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The demarcation is in line with the Law on the Territorial Sea and Contiguous Zone promulgated by China in 1992, according to Chinese state tabloid The Global Times, citing the ministry's Department of Boundary and Ocean Affairs.

The department said on its official WeChat account that the move was necessary to exercise China's sovereignty and jurisdiction.

Located in the northwestern part of the South China Sea, the Gulf of Tonkin is enclosed by Vietnam's northern coastline and China's southern territories including Hainan Island.

Baselines are crucial reference points under the UN Convention on the Law of the Sea, or Unclos. Central to maritime claims, baselines define the outer limits of internal waters and form the basis for marking maritime zones such as a country's exclusive economic zone.

Troy Lee-Brown, Research Fellow at the University of Western Australia Defence and Security Institute, said the lack of an official response from Vietnam was likely due to Hanoi's wish to discuss the issue with Beijing in private.

"This new baseline could complicate earlier agreements and other day-to-day maritime activities and endeavours such as fishing," he warned, adding that some maritime experts are concerned that the new Chinese baseline might be a violation of Unclos.

"If things change from the current demarcation line agreement between the two countries, that might be a worse set of circumstances for Vietnam. You would think Hanoi would need to defend its current entitlements by challenging China's baseline," Lee-Brown added.

Isaac Kardon, a senior fellow at the Asia Program at the Carnegie Endowment for International Peace based in Washington, DC, said Vietnam may not have reacted because of a maritime agreement signed by the two countries two decades ago.

"This change amounts to a clarification of the jurisdictional status of [China's] waters within boundaries already agreed by the two parties in their 2004 maritime boundary and fisheries zone treaty," Kardon said.

The agreement followed years of negotiation and debates regarding the rights of China and Vietnam to the maritime areas and resources in the Gulf of Tonkin.

However, China's latest demarcation turns a large part of the northern South China Sea into its internal waters in what were formerly areas undefined by Beijing, according to Kardon.

China's baseline has been significantly "pushed out" from its coast and is some 24 nautical miles beyond what would constitute "normal" basepoints under Unclos.

The "creeping" demarcation appears to be an attempt by Beijing to assert greater control in an important body of water, Kardon added.

"This move should be seen as an inevitable step towards completing China's maritime legal regime, and we should expect the last area without baselines - the [disputed] Spratly Islands - to be next on the list when conditions permit," Kardon said.

Nguyen Khac Giang, a visiting fellow in the Vietnam Studies Programme at the Singapore-based ISEAS-Yusof Ishak Institute, said Vietnam might not have fully grasped the potential impact on its interest resulting from China's action.

"It might refrain from publicly commenting on the issue until all aspects are clearly understood," he said, adding that since the new baseline grants China broader claims over its territorial sea and exclusive economic zone, this could further complicate the maritime situation in the Gulf of Tonkin.

It might also serve as "leverage" for China in negotiations with Vietnam on separate South China Sea issues, Giang noted.

During Chinese President Xi Jinping's meeting with Vietnamese President Vo Van Thuong last December, both countries agreed to promote consultations on joint maritime development and negotiations on the delimitation of sea areas "beyond the mouth" of the Gulf of Tonkin, according to a joint statement.

Both sides also agreed to "refrain from actions that could complicate the situation or escalate disputes", the statement added.

"China has a history of transforming undisputed areas into disputed ones then portraying itself as willing to engage in 'joint development' in regions where its claims clearly lack legitimacy", Giang added.

In 2014, then Vietnamese ambassador to the United States Nguyen Quoc Cuong referred to Triton Island in the Paracel Islands and described "unacceptable" Chinese attempts "to turn an undisputed [Vietnamese] area into a disputed area".

The diplomat said China's deployment of an oil rig and escort ships in Vietnam's waters was a serious violation of Hanoi's sovereignty, adding that the Southeast Asian country has conducted oil and gas exploration and exploitation in its continental shelf and exclusive economic zone for decades.

In 2012, China opened international bidding for some oil and gas lots in an area that was globally recognised as the continental shelf of Vietnam but no foreign company took up the offer.

Due to the Gulf of Tonkin's unique geography, China and Vietnam have overlapping exclusive economic zones and continental shelves in the area and these were laid down in their 2004 agreement, Lee-Brown said.

He considered the timing of Beijing's announcement on its baseline in the Gulf of Tonkin as "odd".

"I am not sure if it can be framed as being connected to other geopolitical issues."

This article originally appeared on the South China Morning Post (SCMP).

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