By Chris Hogg
BBC News, Tokyo
Japan has launched an innovative project to try to protect an exclusive economic zone off its coast.
Japan hopes to plant tens of thousands of coral colonies
Officials are planting coral to increase the land mass of rocky outcrops in Japan's waters.
Six colonies of coral have been planted around Okinotorishima, some 1,700km (1,060 miles) south of Tokyo.
China recognises the outcrop as Japan's territory, but says Tokyo cannot claim rights to the surrounding waters as it does not qualify as an island.
They look like two concrete roundabouts, sitting in the middle of the sea off the southern coast of Japan.
Their combined land mass is just 10 sq m (12 square yards). But these rocky outcrops are important.
According to the Law of the Sea, Japan can lay exclusive claim to the natural resources 370km (230 miles) from its shores.
So, if these outcrops are Japanese islands, the exclusive economic zone stretches far further from the coast of the main islands of Japan then it would do otherwise.
To bolster Tokyo's claim, officials have posted a large metal address plaque on one of them making clear they are Japanese. They have also built a lighthouse nearby.
Rising sea levels
But the problem is that increasing water temperatures are damaging the coral reef that clings to the rocks and provides much of their land mass.
Rising sea levels blamed on global warming are also threatening to engulf them.
If that happened Japan would lose its rights to the natural resources around them.
So officials are now returning coral samples that were taken from the outcrops back to the mainland a few months ago and cultivated in laboratories.
If the experiment is successful they say they will be able to plant tens of thousands of colonies of coral, thereby making the islets bigger.
China, though, says these are just rocks, not islands.
It argues that they should not be the basis for economic claims, no matter how large they are or how much coral is planted on them.