China has been building these mysterious hexagonal structures on reefs the South China Sea

Collage scsCSIS/AMTI/Digital Globe/Amanda Macias/Business InsiderUnidentified hexagonal structures at Fiery Cross, Subi, and Mischief reefs.

In addition to China’s lightning fast construction of military aircraft hangars on reefs in the South China Sea, mysterious facilities have also emerged.

Satellite imagery published by the Asia Maritime Transparency Initiative (AMTI), a unit of the Center for Strategic and International Studies, shows several unidentified hexagonal structures on Fiery Cross, Subi, and Mischief reefs.

The formations are always oriented toward the sea and started to appear in May according to experts at AMTI.

“I’m afraid I can’t comment just yet,” Gregory Poling, director of AMTI told Business Insider about the hexagonal designs. “But the reason we put them out like this is to collect opinions from other experts in the field.”

It has been nearly a month since the Hague-based court invalidated Beijing’s vast territorial claims in the South China Sea. All the while, Beijing maintains ruling has no bearing and continues to build in the region.

All photos republished with permission from the Center for Strategic and International Studies.

Subi Reef

China began working on Subi Reef in July 2014 and has since reclaimed 3,950,000 square meters of land. Currently, Subi Reef remains China's northernmost outpost in the Spratly Island chain.

Read more about Subi Reef »

Mischief Reef

CSIS/AMTI/Digital Globe

Perhaps the most significant portion of the Permanent Court of Arbitration's July 12 500-page unanimous ruling on the South China Sea is the decision on Mischief Reef. According to the ruling, the reef and everything on it legally belongs to the Philippines.

This is in spite of China's reclamation of approximately 5,580,000 square meters of land, and the construction of a 9,800-foot runway, radar nests, and what some experts have speculated is a soon-to-be naval base.

'The court ruled China's initial occupation of Mischief Reef and its construction of facilities there illegal, so every day that China continues to make use of those facilities it is violating international law,' Poling told Business Insider in a previous interview.

Read more about Mischief Reef »

Fiery Cross Reef

Meanwhile on Fiery Cross Reef, China has reclaimed approximately 2,740,000 square meters of land, and it constructed a 9,800-foot runway, a dredged harbour that is large enough to receive tankers and major surface combatants, and a possible radar tower.

Read more about Fiery Cross Reef »

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