On July 14, Indonesia took a major step forward in confronting China’s South China Sea claims with an announcement that it was renaming a part of the sea in its territory the “North Natuna Sea,” becoming in a single step the most important Southeast Asian nation to stand up to Beijing.
That may have come to many as surprise – certainly to the Chinese, who called on Indonesia to stop using the term on official maps and documents with a diplomatic note, written in Mandarin, from the Chinese Ministry of Foreign Affairs to the Indonesian embassy in Beijing.
Nonetheless, the Indonesians are sticking to their guns. The new name encompasses an area north of the Natuna islands that partly falls within China’s “nine dash line,” by which Beijing claims the sea stretching 1500 miles from its mainland coast almost to the shores of Malaysia, the Philippines, Brunei, Vietnam, and Indonesia.
The naming was a reminder of how seriously Indonesia treats its position as the seat of ancient trading empires and the location of some of the world’s strategically most important straits – Melaka, Sunda, Lombok and Makassar. Since he was elected in 2014 President Joko Widodo has made maritime issues central to Indonesia’s foreign policy, building up its navy, arresting and dynamiting dozens of foreign ships caught fishing illegally, and taking a quiet but firm stand on sea rights.
In December of 1957, Indonesia declared that it was an archipelagic state, at the time a revolutionary move and a direct assault on the assumption by the major western powers that territorial seas extended only three nautical miles from actual coastlines, and that the seas otherwise were open to all.
Source : https://www.asiasentinel.com/politics/indonesia-crosses-nine-dash-line/