The Asia Maritime Transparency Initiative (AMTI) says Subi Reef is China’s northern-most outpost in the Spratly Island group and is just 25 kilometres from civilian populations of the Philippines.

It says China has reclaimed almost 4 million square metres of land and is possibly preparing to build a landing strip. It has already built a helipad, and possibly satellite and security infrastructure.

In its natural state, the reef was submerged at high tide.

Read more: http://www.abc.net.au/news/2015-09-22/south-china-sea-islands-before-and-after/6794076