JAKARTA - President Joko Widodo has played down the stand-off between Indonesian and Chinese vessels in the abundant fishing waters off the northwest coast of Borneo, prompting analysts to say that he was trying to reduce tensions and maintain ties between the two countries.

"I asked the Indonesian military (TNI) Commander, are there foreign ships entering Indonesian territorial sea? As it turns out, none," he wrote on Facebook on Wednesday (Jan 8) after visiting a military base on the Natuna Islands.

On Monday, the president asserted that Indonesia's sovereignty was "non-negotiable" in the light of reports that two Chinese coast guard vessels and around 60 Chinese fishing boats were spotted in December in its exclusive economic zone (EEZ), near the Natuna Sea.

Fighter jets and warships were deployed and the foreign ministry also summoned the Chinese ambassador in Jakarta to deliver a diplomatic note protesting against the Chinese encroachment.

Mr Joko, who is more popularly known as Jokowi, said Chinese vessels were in Indonesia's EEZ, which spans 200 nautical miles from a territory's coast, but not in its territorial sea, which is limited to 12 nautical miles.

"In this zone (EEZ), international ships can pass freely, and Indonesia has the rights over the natural resources and to exercise its rule of law" including capturing or chasing away vessels trying to "illegally exploit the natural wealth".

Mr Joko's visit to the Natunas showed that he took the issue seriously, but his latest remarks indicated that he did not want the stand-off to prolong and become heated, analysts told The Straits Times.

"The Indonesian media is portraying this as a matter of sovereignty. Jokowi cannot walk away from an issue of this magnitude and needs to be seen to lead," said Dr Greg Raymond, a research fellow at the Australian National University.

The president also did not want to jeopardise good relations with Indonesia's biggest trading partner and a major investor. Both countries enjoy broad cooperation including in infrastructure development such as the high-speed railway project linking the Jakarta, the capital, with Bandung. The US$6 billion (S$8.1 billion) project is part of Beijing's Belt and Road Initiative to connect China with Asia, Europe and beyond.

"Jokowi is trapped between two interests (sovereignty and economy)," political scientist Arbi Sanit said. "Business with China must not be ruined. Indonesia has a big appetite to develop its infrastructure but it has no money. And China has been investing a lot so it's a difficult situation."

Indeed, Mr Joko's ministers were eager to keep the issues separate. Coordinating Maritime Affairs and Investment Minister Luhut Pandjaitan said: "Let me be clear that the EEZ has to do with the economy and not sovereignty - these are two very different beasts."

As much as Indonesia needs China for investments, the latter is looking at Southeast Asia's largest economy for resources.

In a sign of a softening stance in Beijing, Chinese Foreign Ministry spokesman Geng Shuang said China and Indonesia have been in contact over the issue through diplomatic channels.

In a regular press conference on Wednesday (Jan 8), posted as a statement on the ministry's website, Mr Geng stressed that China and Indonesia had no disputes over territorial sovereignty, but had "overlapping claims of maritime rights and interests in some areas in the South China Sea".

He said: "China hopes Indonesia will remain calm. We would like to handle our differences with Indonesia in a proper way and uphold our bilateral relations as well as peace and stability in the region."

Mr Geng however maintained that Chinese sovereignty over Nansha Islands - the Chinese name for the disputed Spratly Islands in the South China Sea - and sovereign rights and jurisdiction over the relevant waters, a position it said was in accordance with international law.

China claims most of the South China Sea, bringing it into dispute with the Philippines, Brunei, Malaysia, Vietnam and Taiwan.

While Indonesia is a non-claimant state in the dispute, it has clashed with China over fishing rights around the Natuna Islands. Beijing has claimed some of the waters around the Natunas as part of its "traditional fishing grounds".

Military and defence analyst Connie Rahakundini Bakrie said similar incidents would occur in future as there was no continuous surveillance or intensive patrols by Indonesia in the area.

Mr Joko was "overreacting" by visiting the Natunas, she added. In 2016, the president had taken similar actions and visited the area after several maritime skirmishes between the two countries.

She said: "President Xi (Jinping) didn't go there... it seems that there is a management by panic" whenever territorial issues crop up.

National Maritime Institute executive director Siswanto Rusdi said Indonesia has been fending off fishermen from many Asian countries, including China, poaching in its waters for years, and previous presidents and diplomats had always dealt with the matter quietly.

"Claims over waters is an old problem. My view is the president is capitalising on the negative sentiments against China to win public support for himself," he said.

But international law expert Hikmahanto Juwana felt the recent incident was simply China testing the resolve of the new Indonesian government of Mr Joko, who was re-elected in April.

"China did the same when President Jokowi had only served a few years. The new faces should seize this moment to stay true to the position held by the President and Indonesia's foreign policy."