With U.S policies and to control Communist that will use Communist to against it. The fact is, China - Viet Nam are both on this matter and China is on its way to take U.S place if U.S just standing by. Plus, the debt of U.S from China it seems not able to pay and how to get rid of the paying without filling bankcrupcy?
Free Navigation Route is always the leverage U.S going to has, and China is the one whose just claims up to 80% of entire SCS. Which is not acceptable by any nations. So, what U.S going to loose for its future intervene in SCS? What Viet Nam going to loose which is still demand claims for the Islands?