Here's an outline of how a war might be sparked in the South China Sea:
link
The above has been roughly outlined before, but of note in the last few weeks are the following changes to the situation:
1. Chinese generals and/or admirals are openly calling for attacks on US naval vessels in the SCS, and President Xi has done nothing to reign them in, or to cool their hyperbole (hence, this means it is his "official" policy too, at least for domestic consumption, since they would not go out on a limb without his specific authorization – heads will roll, literally, if they do);
2. the USN has said the Chinese Coast Guard and their "fishing fleet" will be considered as naval combatants should they attempt to intercede or halt our lawful freedom of navigation exercises in international waters;
3. and, two USN vessels just sailed between Taiwan and mainland China again, in what is seen as a show of support for the free nation of Taiwan by the USA.
Looks like things are heating up a little early this year.