ITU ABA, South China Sea — The largest natural feature of the Spratly Islands, the hotly disputed archipelago in the South China Sea, is a forested, sun-drenched oval of land, cleaved by a single runway that gives the place the appearance of a raw coffee bean floating in bright blue water.

Called Itu Aba, it is occupied not by China, which has aggressively asserted its territorial claims in the sea, but by its archrival, the self-governing democracy of Taiwan.

The two broadly agree that there is a historical Chinese stake in the South China Sea, but they diverge radically over how to exercise stewardship over it.