Indonesia has been intensifying its patrols in the waters off the Natuna Islands, in the Riau Islands province, following the recent intrusion by Chinese coast guard vessels escorting dozens of Chinese fishing boats into its exclusive economic zone (EEZ).
Since last Friday, the Indonesian military has deployed six warships, one maritime patrol aircraft and one Boeing surveillance aircraft to monitor the situation over the Natuna Sea, Rear-Admiral Yudo Margono told The Straits Times yesterday.
"Our target is to drive Chinese coast guard vessels and fishing boats out of the EEZ," he said.
He added that the Indonesian authorities could take legal measures against Chinese fishing boats fishing illegally in its EEZ.
Two Chinese coast guard vessels, along with around 60 Chinese fishing boats, were found in Indonesia's EEZ near the Natuna Sea on Dec 19 and 24.
In response, the Foreign Ministry summoned China's Ambassador to Indonesia Xiao Qian and sent a diplomatic protest note on Dec 30.
Indonesia said it would never recognise China's "nine-dash line" - Beijing's vaguely defined territorial claim to most of the energy-rich South China Sea - because it did not comply with international law.
China's boundary line encroaches the EEZ waters of Taiwan, Brunei, Malaysia, the Philippines and Vietnam, which have disputed its claims.
In response to Indonesia's protest, Chinese Foreign Ministry spokesman Geng Shuang said last Tuesday that China had sovereignty over the Spratly Islands and their surrounding waters, and that both China and Indonesia have "normal" fishing activities there, Reuters reported.
He did not mention the Natuna Islands, situated to the south-west.
Indonesia responded by rejecting China's historical claims over its EEZ in the Natuna Sea.
Indonesia's Coordinating Minister for Political, Legal and Security Affairs Mahfud MD said on Sunday that Indonesia will "defend its sovereignty" and will not negotiate with China. As the territory around Natuna belongs to Indonesia, bilateral talks on the issue will not be necessary, he was quoted by Tempo.co as saying.
Despite Indonesia's stepped-up efforts to closely monitor the waters, the Chinese coast guard and at least five Chinese vessels have continued to be about 320km from Ranai waters in Natuna yesterday, Mr Nursyawal Embun, director of sea operations at Indonesia's Maritime Security Agency, told The Straits Times.
"We are trying to enforce the law while at the same time, avert an incident at sea," he said, referring to a potential clash between Indonesian patrol vessels and Chinese coast guard vessels.
The agency has deployed one patrol vessel in the ongoing operation, and expects another one to arrive at Natuna soon to support the Indonesian navy's fleet there.
Coordinating Minister for Maritime Affairs and Investment Luhut Pandjaitan said last Friday that the presence of foreign vessels in the Indonesian EEZ was partly attributable to the country's lack of equipment, and the government hoped to buy more patrol vessels to protect its maritime boundaries.
Indonesia said that over the past three years, Chinese naval vessels have repeatedly entered waters around Natuna, its EEZ acknowledged by the 1982 United Nations Convention on the Law of the Sea.
The last incident occurred in 2016, prompting Indonesia to lodge a complaint to China's embassy in Jakarta.
Dr Beginda Pakpahan, a political and economic analyst on global affairs at the University of Indonesia, said the country must prioritise its policies to maintain its sovereignty in its EEZ.
It also needs to engage various stakeholders to protect its EEZ, he added. "The state presence can be materialised through intensified patrols in outer regions. Also the people need to be there - fishing boats and fishermen can explore further the richness of the sea," he said.