The Chinese investigative vessel that had plied the northern Natuna Sea has returned to Indonesia’s Exclusive Economic Zone (EEZ) after a week of retreat, according to vessel tracking data.

Indonesia downplayed the presence of the Chinese Haiyang Dizhi 10, as it did when the ship operated in the area for most of September.

But the Haiyang Dizhi 10 was seen escorted by a Chinese Coast Guard vessel and appeared to be carrying out illegal research activities in Jakarta’s EEZ, said Imam Prakoso, a researcher at the Indonesian Ocean Justice Initiative (IOJI ).

“It is unlikely that he was not carrying out a search activity, especially since they have been in and out of the area for a month. If you look at the diagram, they’re likely to be active for a whole month, ”Imam told BenarNews, an online news service affiliated with RFA.

The United Nations Convention on the Law of the Sea (UNCLOS) requires governments to apply in advance for authorization for marine scientific research in another state’s EEZ, a requirement that China often ignores.

“There has to be firm action. Do they have permission or not? Otherwise, it is clearly illegal because we have clear rules regarding scientific research activities at sea, ”said Imam.

The Chinese research vessel did not commit any violation, according to Lt. Col. Laode Muhammad, spokesperson for the Indonesian Naval Fleet Command 1.

“The North Sea Natuna is the entrance to the ALKI [Indonesian Archipelagic Lanes] and the Singapore Strait. All foreign ships are allowed to pass, not just the Chinese, ”Laode told BenarNews.

“When it comes to international relations, we must avoid conflict and exercise restraint. If we insist on getting on their ship, they won’t accept it and there will be huge consequences, ”Laode said.

On Monday, the Haiyang Dizhi 10 was seen entering the area near the Tuna Block, a major oil and gas field where a submersible rig contracted by Indonesian exploration partners is drilling appraisal wells.

By noon on Tuesday, the ship was firmly back in the lawn mowing grid it created last month while surveying the northern Natuna Sea.

This area is in the Indonesian EEZ but straddles the so-called “nine-dash line” that China draws to claim most of the South China Sea, but is not recognized by international law and is contested by China’s neighbors.

The Haiyang Dizhi operated in the region for most of September, but departed for supplies at Fiery Cross Reef, which China reclaimed and turned into a flagship outpost.

The “Chinese ship did not just pass”

Admiral Dato Rusman, commander of the Marine Combat Group, told President Joko “Jokowi” Widodo during a video conference that Chinese and American ships had been detected in Indonesian waters but were “making an innocent passage”.

“Everything is safe and under control,” he added.

Indonesian authorities have consistently downplayed the Chinese ship’s presence, analysts said, favoring a diplomatic approach and behind-the-scenes negotiations.

For example. Indonesia said last month that the Haiyang Dizhi 10 did not break the rules of navigation. But, analysts said, the movement of the Chinese grid ship showed it was clearly engaged in research activities.

Likewise, IOJI’s imam did not appear convinced by Rusman’s explanation on Tuesday about the latest Chinese incursion.

“The boat [Haiyang Dizhi 10] did not just pass [by]”, noted Imam.

“He formed a grid that covers part of the North Sea Natuna, which lies in the line of nine dashes that they have [China] Claim.”

The activities of the Haiyang Dizhi 10 last month garnered media and public attention, prompting Indonesian officials to send warships as well as conduct an air patrol.

On Tuesday, Indonesian Armed Forces Day, the navy held a combat readiness exercise in the northern Natuna Sea. Six warships, a maritime patrol aircraft and a helicopter took part in the event.

Indonesia has also deployed a hydro-oceanographic research vessel, the KRI Rigel, to the region.

President Jokowi is said to have questioned his staff about the presence of foreign ships off the Natunas and called on the armed forces (TNI) to stand ready to face a series of threats.

“I call on the TNI to be constantly prepared for a wider range of threats, including violations of sovereignty, the theft of natural resources at sea, radicalism and terrorism, as well as cyber and biological threats,” said said Jokowi.

Governments of countries bordering the South China Sea face increasing domestic pressure to defend national interests amid China’s assertive activities.

Malaysia summoned the Chinese ambassador on Monday to brief him on its position and protest “against the presence and activities of Chinese vessels, including a survey vessel, in the Malaysian EEZ off the coasts of Sabah and Sarawak “.

Reported by BenarNews, an online news service affiliated with RFA.