The territorial claim that can be seen from space

The South China Sea is bound by China, Taiwan, and several southeast Asian nations. China claims jurisdiction over most of it, but countries like Vietnam and the Philippines claim territorial rights over some islands and areas.

There are signs these disputes are starting to intensify. A recent satellite image of Triton Island, one of the Paracel Islands which China exercises effective control over, showed a Chinese flag painted onto the ground. The Chinese characters for "Long Live the motherland" could also be seen.

Accelerating development

NHK obtained satellite images taken between September 2022 and October 2023. They showed that a road-like runway had been constructed in the middle of Triton Island.

According to the Center for Strategic and International Studies (CSIS), an American think tank that studies territorial disputes in the South China Sea, the road-like structure is approximately 600 meters long and 15 meters wide. Some media outlets initially suggested it was an aircraft runway, but CSIS says this is unlikely due to the short length and lack of a taxiway.

Instead, the think tank believes it could be a levee or an elevated road. The north side of Triton Island is prone to flooding, and such a structure could help stem the flow of water to the west and south sides, where construction is currently underway. Satellite images show the development of structures resembling a helipad and a basketball court.

"It's an important outpost in terms of having a presence close to Vietnam," says Harrison Pretat, deputy director of CSIS. "So it's not something China wants to wash away or get washed away by the ocean. So it's definitely going to ensure that outpost remains functional and they're expanding it."

China claims jurisdiction inside a boundary line called the "Nine-Dash Line," which includes almost the entirety of the South China Sea. It has been carrying out land reclamation efforts throughout the area to create artificial islands for military bases and radar facilities.

According to CSIS, China has reclaimed 16 reefs in the South China Sea over the past decade, creating nearly 16 square kilometers in land.

Vietnam plays catch-up

Satellite images show Vietnam started proceeding with land reclamation projects of its own in the second half of 2022.

An image of the Pearson Reef in the Spratly Islands, taken in May 2022, shows an oval landmass in the north. That December, it had expanded to cover most of the reef.

Tennent Reef is located approximately 100 kilometers east of Pearson Reef. Satellite imagery from March 2022 shows just a thin trip of land. Nine months later, it had expanded considerably. Development work has continued this year, with images showing a new port on the north side of the island.

The island Vietnam has developed the most is Barque Canada Reef. As of June 2022, it was an atoll with small strips of land in the northwest and southeast. By that November, both sides had expanded considerably, with CSIS estimating the atoll had grown by 0.8 square kilometers. This made it the largest reef under Vietnamese control in the South China Sea.

In total, CSIS says Vietnam has reclaimed 20 reefs with a total area of approximately 3.5 square kilometers.

Changes to landfill methods help Vietnam speed up reclamation efforts

Meanwhile, CSIS points out that Vietnam's land reclamation methods have changed too. In the past, boats that dredged earth and sand used a method that picked up sediment from shallow waters. This is considered to be less harmful to the environment.

However, in 2022 Vietnam started excavating the seabed and pumping up sand. This allows reclamation crews to dig deeper in a shorter amount of time. It is a method also favored by China.

CSIS says the facilities that Vietnam has developed will likely be used as refueling points or safe havens for coast guard vessels and fishing boats.

A spokesperson for Vietnam's Ministry of Foreign Affairs stressed the validity of its activities in the South China Sea at a press conference last month. Pham Thu Hang said there is sufficient historical evidence to support Vietnam's sovereignty over the reefs, adding the activities are completely legal under international law.

Boosting patriotism with government-sponsored tours

The Vietnamese government has been conducting tours to parts of the Spratly Islands it effectively controls for the past decade.

Approximately 40 Vietnamese took part in a tour in May 2022, according to one participant. They included people living in the United States, Japan, and Europe.

During the 13-day tour, participants traveled on a naval vessel and visited a total of ten reefs and oil fields. They also landed in inhabited areas where they toured schools and temples.

"It was a meaningful experience," said the participant. "Many Vietnamese including myself want to learn about the situation surrounding our country`s sovereignty."

Future of the disputes

In April 2020 the Vietnamese government lodged a protest with China, claiming a Chinese government ship collided with and sank a Vietnamese fishing boat in the Paracel Islands.

Meanwhile, in August 2023 a Philippine military transport ship was headed to a base in the Spratly Islands when it was sprayed with water by a Chinese government ship. Two months later, Manila announced a Philippine military transport ship had collided with a Chinese ship after repeated dangerous approaches in the same area.

The Association of Southeast Asian Nations is attempting to formulate a legally binding "code of conduct" to rein in China's maritime expansion. But these efforts are not progressing. Countries like Vietnam that are embroiled in territorial disputes with China may see strengthening their own claims as the only viable way forward.