In any negotiation must stake claim first so that there is something to negotiate.
Fact of matter is that China is going to be giant gorrilla (economy wise) in this part of the world and they know that. US can have the strongest military but that is only useful in a shooting match and will not be influential here economically. As it is Japan currently has more influence economy wise in this region.
What counts is business. For example, Philippines want to export coconut produce, China buys all. Philippines want to build infrastructure - China offers financing in exchange for purchase of Chinese trains.
For example Spratleys we have numerous countries within Asean claiming that territory. So China comes into the mix as the giant. They put trade and financing on table and in exchange get some shared ownership to drill for oil.
Think about this scenario. China offers the $$, offers long term contract for any oil found there and revenue split amongst Vietnam, philipines, malaysia and China. % is part of negotiation.
With so many counter claims if China can get, say Malaysia and Philippines on their side then Vietnam has no choice.
But before that we see claims and counter claims, military ships, etc etc. In the end, China wants the oil. So it will be a business deal. Just like in malaysia - Bumi gets license, collects that 20% royalty risk free and Chinese do everything else (come up with capital, equipment, everything) but gets 80%.
So for Spratleys - maybe China comes up with all $ and expertise and gets 45% stake and the 55% split among Vietnam, malaysia and philippines.