New satellite images show China is making significant progress in constructing a runway on the Subi reef, in disputed territory in the South China Sea. The images show construction of a runway which, if completed, could provide China with another combat-capable air facility in the region.

The images, taken on Sept. 3 and published in the Diplomat, show a subgraded area of land approximately 60 meters wide by 2,200 meters long. The land Chinese forces have reclaimed around the reef could eventually accommodate a runway of up to 3,300 meters suitable for most of China's combat and support aircraft, the magazine said.

If China's work on the Subi reef results in a military air facility, it will be China's third in the region, which several of its Asian neighbors claim territorial rights to, and raises the prospect of Beijing attempting to use its rising military power in the disputed region.

South China Sea runway A Sept. 3 satellite image shows a runway being constructed by Chinese forces on reclaimed land around the Subi reef in the South China Sea. Photo: The Diplomat / Digital Globe

In 2013, China established an air defense identification zone in the East China Sea, which encompassed territory claimed by Japan, as well as territory regarded as international waters by other countries, including the U.S. 

U.S. and Japanese aircraft have deliberately flown through the zone without identifying themselves to the Chinese, to emphasize their rejection of any Chinese sovereignty over the area.

China has claimed the majority of the South China Sea as its territory, with its so-called “nine-dash line" boundary, which it says represents its historic areas of interest.

A report from the Pentagon released in August found that China had dramatically increased its land-reclamation activities in the disputed Spratly Islands in the South China Sea, and was using naval patrols to aggressively assert its territorial claims in the region.