Nevermind what some of the keyboard warriors here say. They don't count, as they have 0 power outside of their PDF fantasy land. Seriously and logically speaking. What are the chances China would attempt to sink a USN ship (first strike) knowing full well that would mean immediate retaliation from the USN. No rational Chinese leader wants to see that happen. That would basically be the only way I could see the US getting involved in a military manner.
I know China right now or in the future try their best to avoid confrontation with US, naval war like a boxing match in a boxing ring, only 1 heavy weight will fight against 4 middle weight + 1 heavy weight in the SCS. Odd will always be against China in a naval battle in SCS.
If that is how Vietnam and Philippines want to play this game out, we are okay with it. We drill, we get 100% of the oil profit. Vietnam and Philippines drill, they get only a partial percentage of the profit. Let see who win more.
Then why not China and Vietnam drill oil together to share the profit? one less nations to worry about in SCS. Now China won't be surround in the naval battle.