How does Indonesia deal with overlapping claims of a country it doesn't recognise as a neighbour?

I Made Andi Arsana, a lecturer at the Department of Geodetic Engineering, Gadjah Mada Universit, Yogyakarta, tells of a surprising question at a recent lecture.

A participant asked him about a country that Indonesia does not recognise as a neighbour but acts like one. He was referring to the People's Republic of China.

"As reported in 2009 and 2010, Chinese fishermen came to fish in the waters north of Indonesia’s Natuna Islands," Mr Arsana recalled in The Jakarta Post. "Pursuant to the Law of the Sea, the water area falls under Indonesia’s territory or jurisdiction. Should maritime division be required in the area, it is the business of Indonesia and other countries, the maritime entitlement of which extends up to the South China Sea.

"The question is whether or not China’s maritime entitlement extends up to the north of Natuna Islands?"

In a verbal note to the United Nations in 2009, China stated that: “China has indisputable sovereignty over the islands in the South China Sea and the adjacent waters …” This asserts Chinese claim over land territory and maritime areas to the north of Indonesia’s Natuna Islands, which is also disputed by other countries in the region.

"On the other hand, Indonesia does not claim any small island in the South China Sea, and does not consider China as a neighbor in the context of maritime delimitation. Indonesia only considers Malaysia and Vietnam as its neighbors with which maritime boundaries need to be settled in the South China Sea," Mr Arsana points out. "In other words, Indonesia does not even see that it has to deal with China when it comes to maritime entitlement in the South China Sea."

This Chinese claim, as also depicted in its 2009 note to the UN, started in the late 1940s when a map depicting a broken line in the South China Sea was published. The line, also known as the nine-dotted line, indicates Chinese claim extending to a maritime area close to Indonesia’s Natuna Islands.

However, there has been no clarification whether the line indicates Chinese claims over small islands (eg Spratlys, Paracels, etc) in the South China Sea only, or also over maritime areas enclosed by the line.

Meanwhile, in its own note in 2010 to the UN, Indonesia did not recognise China’s claim over maritime areas enclosed within the line.

"While Indonesia has been consistent not to acknowledge China as one of its maritime neighbors, it seems China has a different view," Mr Arsana says. "To overcome this, the very first thing required is clarification from China regarding the extent of its territorial, and particularly maritime, claims in the South China Sea."