The government of Indonesia inaugurated a military base in the Natuna Islands on Tuesday, in the South China Sea and near disputed territory that China has increasingly colonized using the manufacture of artificial islands and illegal coast guard patrols.

The Natuna Islands are part of Indonesia’s exclusive economic zone and not claimed by China. China does claim the waters off the those islands, however, despite an international court ruling from 2016 declaring that China’s extraterritorial claims in the South China Sea are all illegal.

President Joko Widodo made clear on Wednesday that the new base, likely the first in a series, is a response to pressure from China to protect Indonesian territory, as neighboring countries have failed to do the same for their lands and waters.

According to Japan’s Kyodo News, the Natuna Besar Island military base will host over a thousand personnel and serve as a “deterrent” for Chinese colonialism, according to Indonesian Defense Force chief Marshal Hadi Tjahjanto. Hadi said during remarks at the opening of the base that among that personnel will be an army battalion, marines, and engineers. Kyodo estimated the total number of troops stationed there by noting that Indonesian army battalions typically range between 825 and one thousand troops in size.

The Indonesian government has provided few additional details about this base, though Hadi reportedly suggested that it will be the first in a series on nearby islands if Jakarta deems them necessary for national security.

Widodo issued comments Wednesday defending Indonesian sovereignty in Natuna, not specifically referring to the new base but asserting that he was ready to fight China, or any other claimant, for the resource-rich territory.

“If you want us to fight, yes, together we will do it,” Widodo said during a speech at an unrelated event. The president claimed that, in 2016, when China first began making overlapping claims with Indonesia’s territorial waters, “I was really upset, I took a warship to Natuna” and prepared to defend it personally. He repeatedly described Indonesia’s claim to the Natuna Islands as “obvious” and asserted that the 169,000 people who live there are ethnic Indonesians.

Indonesia is one of several nations with concerns that China is attempting to usurp its territory. The Chinese Communist Party claims territory in the South China Sea belonging to Brunei, Taiwan, Vietnam, the Philippines, and Malaysia, in addition to the Natuna waters, if not the islands themselves.

Indonesia, as Widodo noted, increased its vigilance over the Natuna Islands in 2016, following a dramatic increase in the number of Chinese vessels attempting to fish illegally in Indonesian waters. In March of that year, the Indonesian government attempted to seize a Chinese warship illegally fishing in its territory and arrest its crew. The Chinese Coast Guard sent several vessels over to repeatedly ram the seized ship until Indonesian authorities were forced to let it go or allow the Chinese to sink their own vessels. Beijing insisted its presence there was legal because the Natuna waters are “traditional Chinese fishing grounds,” citing no evidence.

Later that year, Indonesia’s legislature approved a ten-percent increase in defense spending specifically to protect from Chinese attacks. Jakarta subsequently also moved to rename the region where the Natuna Islands lie as the “North Natuna Sea,” separate from the South China Sea. The government registered the new name through the International Hydrographic Organization (IHO) and the United Nations, the latter which would theoretically change the parameters used to apply the U.N. Convention on the Law of the Sea (UNCLOS). The announcement triggered an outraged response from Beijing.

China has diverted much of its attention in the region elsewhere – namely, in the Spratly and Paracel Islands shared by Vietnam and the Philippines. Under President Rodrigo Duterte, the Philippines has nearly completely stopped challenging China on its claims to Manila’s waters. Vietnam has expressed significant concern but does not boast a military large enough to credibly challenge China’s claims. As recently as last month, satellite images showed new Chinese constructions in the Paracel Islands, where Beijing has already built islands equipped with advanced surveillance and military assets. China claims these assets are necessary for search and rescue operations in the event of an emergency, citing the disappearance of Malaysia Airlines Flight 370 in 2014, which has yet to be found.

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