The simmering dispute in the contested South China Sea is about to turn to a boil.

With an international arbitration court ruling on the legality of China's "nine-dash line" claim to much of the South China Sea set to be handed down in the coming days or weeks, experts say the situation is likely to get a lot more complicated in the months and possibly years ahead.

The case, brought before the Permanent Court of Arbitration (PCA) at The Hague by the Philippines, is widely expected to end in a ruling favoring Manila, which says that Beijing's claims violate United Nations Convention on the Law of the Sea (UNCLOS) agreements about territorial seas and exclusive economic zones (EEZ).