China and South Korea are looking for a demarcation of the South China Sea

Strategic passage

Every year, $5 trillion in shipping trade passes through the South China Sea. Besides China, there is Vietnam, the Philippines, Malaysia, Taiwan, and Brunei vying for the control over disputed waters. If the Pacific area is an important transit zone of the world economy, the South China Sea is simply a "heart-sea" if speaking in geopolitical terms.

Multilateral tensions and US interests
South Korea has been an ally of Washington for a long time, since 1953. There are  US military base emplacements and materials were increased recently. The White House may to use South Korea as a proxy against both China and North Korea. But economically, South Korea depends on China.
 
The Philippines also have a claim on the South China Sea and President Benigno Aquino vowed on Monday Dec. 20th to leave behind a stronger and a more capable armed forces to face maritime challenges there. He promised to spend $1.77 billion until 2017 to strengthen the military, as China asserts its claims to most of the waters. Washington also supports the Philippines and already has transferred two former coast guard cutters and transport planes to this country.
 
China and Vietnam agreed to launch joint inspections on the waters outside the mouth of the Beibu Gulf in December.
 
The US provokes Bejing in different ways. Xinhua noted that a recent flyover by two U.S. bombers near Chinese islands in the South China Sea were an intentional incident, as every other maneuver by Washington aimed at sustaining its global hegemony. Also China was displeased that Obama's administration authorized a 1.83- billion-U.S.-dollar arms sale package to Taiwan.
Forecast

If negotiations will succeed it may be an example of good Chinese efforts at peaceful cooperation and coexistence. It will be difficult to implement one model for every country involved in the conflict, because interests and approaches are different. Also the US will try to engage in this dispute for its own goals. At any rate, the beginning of this process is good for the normalization of relations.