“That is why the president has instructed us not only to continue to patrol the waters but to develop the economy of the Natunas. If the economy in the Natunas is alive, then we can maintain the country’s unity.”

Analysts said the ministers’ visit to the islands – a flashpoint in an otherwise strong relationship between Indonesia and China – was probably aimed at reassuring their 81,000 residents, and Indonesians in general, that Jakarta took seriously reports of recent Chinese activity in the area despite its lack of action on the diplomatic front.

“These publicised trips, I believe, are meant to assure the locals that the Indonesian government under the Joko Widodo administration remains invested in the development and security of the Natuna Islands,” said Collin Koh, research fellow at the Institute of Defence and Strategic Studies in Singapore.

“The government’s relative silence on this issue despite the media reports might have come across as unsettling to the domestic constituents who might argue Jakarta is bending over to Beijing for the sake of not rocking the boat in bilateral relations long underpinned by economic benefits.”

Chinese survey ships have in recent months been spotted lingering in the North Natuna Sea, at times flanked by Chinese coastguard vessels. The Chinese vessels allegedly conducted seabed mapping near an oil and gas drilling field.

As a response, Indonesia has sent naval ships and air patrols to the area, but no firm diplomatic actions have been taken so far. The Indonesian Maritime Security Agency has brushed off concerns by saying that the Chinese vessels were probably heading to international waters.

Mahfud said Widodo was aware of the presence of the vessels. Mahfud reiterated that Jakarta’s aim was to maintain Indonesia’s good relationship with China while solving the territorial issue via diplomacy.

“At the beginning of 2020, when Chinese vessels really provocatively entered Natuna waters, the president came here and stated that this is our territory. Chinese vessels ultimately understood the message and retreated,” he said.

“We also summoned China’s ambassador to Indonesia and we talked not as enemies, we talked about how we have good relationships and how we should try not to let the Natuna issue damage this. That’s how we talk [with China], through diplomacy.”

Economic boost

Jakarta’s economic approach underlines long-running concerns.

“On one hand, Indonesia does not want to be seen as worried that it will lose its outermost islands, but on the other hand they are concerned that these islands might be annexed or bought by other countries,” said Yohanes Sulaiman, lecturer in the School of Government at Jenderal Achmad Yani University in Bandung, Indonesia.

“The government has long believed that a strong economy will strengthen the nation’s unity, particularly in border areas.”

Home affairs minister Tito Karnavian said during his visit to the islands that Jakarta acknowledged “overlapping border claims”.

“We do not want even an inch of our country’s borders, territory to split from us, as has happened with Sipadan and Ligitan islands, thus we are strengthening our borders,” he said.

Sipadan and Ligitan in the Celebes Sea have been part of a border dispute between Indonesia and Malaysia since 1969. The International Court of Justice decided in 2002 that both islands belonged to Malaysia.

“In the Natunas, particularly, we know that there are overlapping border claims. Vietnam thinks their exclusive economic zone falls within our territory. Secondly, we know China also claims the nine-dash line as their traditional fishing ground, so their fishing vessels enter our territory. We do not recognise that,” the minister added.

Tito said Jakarta planned to build more housing and 38 telecommunication towers on the islands. It would also boost the quality of education.

In December, Indonesia said it was planning to move a naval combat squad headquarters to the Natunas. It is also constructing a US$3.5 million maritime training centre with the United States in Batam, where the Malacca Strait meets the South China Sea.

Last week in Washington, the Pentagon hosted the 19th annual Indonesia-United States Security Dialogue, at which the two sides agreed to strengthen their defence partnership by expanding joint exercises and enhancing collaboration on maritime initiatives.