Natuna islands are not claimed by China. The dispute is the maritime boundary (the waters), not the islands. China did not add anything to the original nine dash line or advanced its claims further, this dispute was known decades ago.
Natuna Islands
Natuna Islands
The Natunas, some 400 miles northeast of Sumatra, have been a subject of dispute since 1993, when Beijing published a map showing Chinese "historic claims" on a gas field northeast of the islands. Jakarta rejected these claims as without basis in international law.
China has since sought to reassure Indonesia that it does not lay claim to the Natunas, nor all the waters of the South China. China renounced its claims on the Natunas in 1995, but not the gas field....
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China does not claim the Natuna Islands themselves, considered Indonesian territory, PRC maps of the region include the waters just north of the Natunas. Indonesia insists the area is part of its EEZ. These waters cover part of the world’s largest offshore gas fields. With an estimated 1.27 trillion cubic meters of recoverable gas, they represent 40% of Indonesia’s gas reserves.......