Naval ships often track their countries’ oil rigs and fishing expeditions. Oil, natural gas, and fish explain why the 3.5 million square kilometers (1.4 million square miles) of water stretching from Singapore to Taiwan are so sought after.
The past three decades have seen countless military clashes: One occurred in 1976, when China took the tiny, uninhabited Paracel Islands from Vietnam. Another came in 1988, when China and Vietnam clashed in the equally miniscule Spratly Islands, according to the US-based public policy organization GlobalSecurity.org. The 1988 incident sank Vietnamese boats and killed 70.
So agreements are popular between the smaller claimants that, in addition to Vietnam, include Brunei, Malaysia, Taiwan, and the Philippines. They want a safety net against China, which is ranked No. 3 in the world in terms of military might.
A 1999 regional code of conduct largely written by the Philippines was directed at containing China. In April this year, vessels from China and the Philippines were locked in a standoff over Scarborough Shoal, a South China Sea landmark west of Luzon Island.