In fact, people who has read Chinese books of tactics can understand China's actions.
- In 1974, CN used "趁火打劫" to took Paracel Islands when Vietnam engulfed in a civil war.
- In 1979, CN used "圍魏救趙" to helped Khmer Rouge (But I think you did not successfully).
- In 1988, CN used "遠交近攻" to took some islands of Spratly without reactions of Soviet Union.
- Now, CN using "無中生有" to makes not disputed area becomes disputed area, "釜底抽薪" with economic aid for Lao, Cambodia,... to isolates Vietnam and The Philippines in ASEAN.
-...
One day, I think a "dead body" will be creat in the SCS to make a reason for your military actions. Soon or late will depends on situation.