Beijing claims it closed off part of the South China Sea to hunt for a lost Shaanxi Y-8 aircraft. Photo: Wikipedia

On March 4, China closed off an area in the South China Sea for “military exercises” until March 15. The area is southwest of Hainan between China and Vietnam and includes part of Vietnam’s claimed exclusive economic zone (EEZ) and continental shelf (see map). 

Area ‘closed’ for China’s military drills, and Vietnam’s claimed EEZ.

According to Taiwan’s intelligence agency, China is using these drills as a cover to search for a lost Y-8 submarine-hunting aircraft. Vietnam protested and asked China to respect its EEZ and continental shelf. But China rejected the complaint, saying, “It is reasonable, lawful and irreproachable for China to conduct military exercises on its own doorstep.”

China’s action raises several legal questions and invites comparison with similar US actions in the Philippines’ claimed EEZ as it searched for and on March 2 recovered its lost F-35C advanced stealth fighter.

If it is true that China lost an advanced submarine hunter, some general circumstances are similar. Both China and the US declared an area of “international waters” off limits to recover a lost warplane. 

But that’s where the similarities end.

First of all, the US acknowledged that it had lost a warplane. It had no choice because videos of the event surfaced on the Internet. China has not acknowledged that it lost an aircraft.

But much more important is the fact that the US loss and search took place within the undisputed Philippine EEZ and continental shelf. Moreover, the US gave a “warning to mariners,” which is technically not a closing off of the area. Others can enter at their own risk. 

In China’s case the alleged loss and subsequent recovery effort are in a “closed area” in disputed waters. Vietnam and China have an agreed boundary in the Gulf of Tonkin. But that boundary ends northwest of the “closed area” in question (see map).

So the boundary in the area in question is still in dispute. It is not – as Vietnam might claim – a matter of simply extending the trajectory of the already agreed boundary. While part of the area does fall within 200 nautical miles of Vietnam’s coast and thus within its claimed EEZ and continental shelf, China also has a claim to the area.

Beijing could argue that the Paracels – claimed by China but occupied by Vietnam – belong to China, that they are legal islands, and that they generate an EEZ and a continental shelf extending out to 350nm. This plus the effect of the large island of Hainan could push the boundary closer to Vietnam.

According to the United Nations Convention on the Law of the Sea (UNCLOS), a state has sovereignty over the resources in its EEZ and its continental shelf and a responsibility to protect the environment. But many states – led by the US – assert freedom of navigation on the high seas and that military exercises are internationally lawful uses of the sea even within the EEZs of other states.

But declaring a ban on vessels in an area claimed by another country is still controversial.

UNCLOS says that foreign vessels exercising their rights in a country’s EEZ must have “due regard” for the rights and duties of the coastal state as well as for the interests of other states exercising their high seas freedoms. They must not present a hazard to navigation by others.

Both China and the US seem to be in violation of this provision, although the Philippines may have given permission for the US actions in its EEZ. 

Moreover, it is not clear what Vietnam’s objections are based on. Does it claim a violation of “due regard”? Is it objecting to foreign military activities in its claimed EEZ in general or because they may damage its environment or biological resources? These would be new positions for Vietnam.  

Perhaps it is concerned about China’s use of marine scientific instruments in its search for the aircraft in its claimed EEZ without permission. If so, this would also be a new position for Vietnam.

To retrieve its aircraft from the Philippine EEZ and continental shelf, the US Navy had to locate it by remote sensing, use a remotely operated vehicle (ROV) to attach cables to it and then raise it to the surface. The ROV was equipped with sophisticated sonar and digital and TV cameras.  

Indeed, all these tasks required the use of advanced technological instruments in the Philippine EEZ. Under UNCLOS – which, unlike China and the Philippines, the US has not ratified but claims to abide by – “marine scientific research” can only be undertaken in a country’s EEZ with its permission. 

The US tries to differentiate between marine scientific and military surveys in the EEZ, arguing that the latter do not require the consent of the coastal state.

But UNCLOS Article 258 stipulates that “the deployment and use of any type of scientific research equipment in any area of the marine environment shall be subject to the same conditions as are prescribed in this Convention for the conduct of marine scientific research in any such area” – that is the consent regime. 

The US Navy used “scientific research equipment” in the Philippine EEZ and should have and may have had Philippine government permission to do so. The Philippines has been silent on the matter. 

These actions raise several important legal questions that need clarification lest they set a precedent for future situations.

Mark Valencia

Mark J Valencia is an internationally recognized maritime policy analyst, political commentator and consultant focused on Asia. Most recently he was a visiting senior scholar at China’s National Institute for South China Sea Studies and continues to be an adjunct senior scholar with the Institute. Valencia has published some 15 books and more than 100 peer-reviewed journal articles.