In today's world, many governments use nationalism to help control their domestic situation. China, Japan, Philippines, Malaysia, Vietnam all do that; and one way in which they do that, is by claiming some territories in the South China Sea. Other nations (like the US, Russia, etc.) are concerned about who will end up winning the argument: everyone wants their regional allies to win, and their adversaries to lose.
All these claims are just a boring old geopolitical game, which has been played over land control for as long as sovereign states existed (and it was modified only slightly from the tribal times).
There's nothing "fair" or "right" or "reasonable" about these games. It might seem as a zero-sum game since only one country can usually own a given piece of land. But actually, it's not zero-sum: each government increases its domestic popularity by yelling loudly about how the evil neighbors are taking away what "rightfully" belongs to their own nation.
If you want to read more about this, I can recommend these articles:
Even the word "disputed" is too kind. The U.N. rejects the claim, which is based on fantasy (and force), only, not history. It doesn't even rise to the standard of revanchism or irredentism, which are disreputable, too.
All these claims are just a boring old geopolitical game, which has been played over land control for as long as sovereign states existed (and it was modified only slightly from the tribal times).
There's nothing "fair" or "right" or "reasonable" about these games. It might seem as a zero-sum game since only one country can usually own a given piece of land. But actually, it's not zero-sum: each government increases its domestic popularity by yelling loudly about how the evil neighbors are taking away what "rightfully" belongs to their own nation.
If you want to read more about this, I can recommend these articles:
https://worldview.stratfor.com/article/risky-business-south-...
https://www.lawfareblog.com/south-china-sea-dispute-brief-hi...