A large communications-sensor array was completed on Fiery Cross Reef in 2017, according to the Centre for Strategic and International Studies of the Asia Maritime Transparency Initiative (AMTI).

The AMTI released its analysis comparing their satellite photos with the aerial photos released early this month.

“None of the other bases in the Spratlys so far has a comparable array, though smaller ones have been built on Subi and Mischief, suggesting that Fiery Cross might be serving as a signals intelligence/communications hub for Chinese forces in the area,” the AMTI said.

Fiery Cross Reef had the most construction among China’s seven artificial islands in the Spratlys, with work spanning 100,000 metres, according to the research organisation.

“Why are we not protesting China’s militarisation of [Fiery Cross] Reef? It is outside our exclusive economic zone (EEZ) but too close for comfort,” said former national security adviser Roilo Golez in a Facebook post.

“Combat planes to be deployed there can reach Palawan and parts of Mindanao within minutes. Like [Mischief] Reef, it is also a threat to our national security. This is not a good faith act, but a hostile act,” he also said.

All the biggest three fortified bases of China — Fiery Cross, Mischief, and Subi — have three-kilometre runways.

Further, the AMTI observed that the underground storage tunnels likely for ammunition and other materiel in Mischief Reef have been already buried, based on the Inquirer photos.

Buried tunnels

“In the Inquirer’s photo, the tunnels are already buried, but AMTI’s satellite image shows the tunnels in an earlier, exposed state. Identical buried storage facilities have been constructed at Fiery Cross and Subi Reefs.

There is also more underground storage built along the north side of Mischief (and at Fiery Cross and Subi),” the AMTI noted.

Mischief is within the Philippines’ EEZ. The arbitral tribunal also ruled in 2016 that it belongs to the Philippines.