Indonesia's president visited the Natuna Islands aboard a warship on Thursday, making a bold move to assert sovereignty over the area in the southern reaches of the South China Sea after Beijing stated its "over-lapping claim" on nearby waters.
President Joko Widodo's visit along with his chief security minister and foreign minister was described by Indonesian officials as the strongest message that has been given to China over the issue.
A presidential palace statement said Widodo intended to hold a cabinet meeting aboard the warship.
"In the course of our history, we've never been this stern (with China). This is also to demonstrate that the president is not taking the issue lightly," Chief Security Minister Luhut Pandjaitan told The Jakarta Post newspaper.
Beijing said on Monday that while China does not dispute Indonesia's sovereignty over the Natuna Islands, "some waters of the South China Sea" were subject to "overlapping claims on maritime rights and interests".
Indonesia's Foreign Minister Retno Marsudi on Wednesday rejected China's stance, saying the waters around Natuna are in Indonesian territory.
There have been a series of face-offs between Indonesian and Chinese vessels in the area but both sides have denied that the matter is a territorial or diplomatic dispute.
Widodo's visit to the remote island chain, which lies over 340 kilometers (212 miles) off the northwest tip of Kalimantan - Indonesia's portion of Borneo island - was also aimed at promoting infrastructure development in Indonesia's border areas.
"We want to show that Indonesia is a big country and we have to show this physically," Widodo said in a statement, referring to those infrastructure ambitions.