International attention has shifted away from the slow-moving crisis in the South China Sea over the course of 2017, but the situation on the water has not remained static. While pursuing diplomatic outreach toward its Southeast Asian neighbors, Beijing continued substantial construction activities on its dual-use outposts in the Spratly and Paracel Islands. China completed the dredging and landfilling operations to create its seven new islands in the Spratlys by early 2016, and seems to have halted such operations to expand islets in the Paracels by mid-2017. But Beijing remains committed to advancing the next phase of its build-up—construction of the infrastructure necessary for fully-functioning air and naval bases on the larger outposts.

AMTI has identified all the permanent facilities on which China completed or began work since the start of the year. These include buildings ranging from underground storage areas and administrative buildings to large radar and sensor arrays. These facilities account for about 72 acres, or 290,000 square meters, of new real estate at Fiery Cross, Subi, and Mischief Reefs in the Spratlys, and North, Tree, and Triton Islands in the Paracels. This does not include temporary structures like storage containers or cement plants, or work other than construction, such as the spreading of soil and planting of grass at the new outposts.

Fiery Cross Reef

Fiery Cross saw the most construction over the course of 2017, with work on buildings covering 27 acres, or about 110,000 square meters. This counts work previously documented by AMTI, including completion of the larger hangars alongside the airstrip, work on large underground structures at the south of the island likely intended to house munitions or other essential materiel, a large communications/sensor array at the northeast end of the island, various radar/communications facilities spread around the islet, and hardened shelters for missile platforms at the south end.

The large underground tunnels AMTI identified earlier this year as likely being for ammunition and other storage have been completed and entirely buried. They join other underground structures previously built on the island, which include water and fuel storage.

In addition to the work previously identified at Fiery Cross, in the last several months China has constructed what appears to be a high frequency radar array at the north end of the island. It consists of a field of upright poles, similar to those erected at Cuarteron Reef in 2015. This high-frequency radar is situated next to the large communications/sensor array completed earlier in the year (the field of radomes in the image below).

Subi Reef

Subi Reef also saw considerable building activity in 2017, with work on buildings covering about 24 acres, or 95,000 square meters. This included buried storage facilities identical to those at Fiery Cross, as well as previously-identified hangars, missile shelters, radar/communications facilities, and a high-frequency “elephant cage” antenna array for signals intelligence at the southwest end of the island.

Like at Fiery Cross, the new storage tunnels at Subi were completed and covered over in the last few months. They join other buried structures on the islet, including large storage facilities to the north.

China is poised to substantially boost its radar and signals intelligence capabilities at Subi Reef. Since mid-year, it has built what looks like a second “elephant cage” less than 500 meters west of the first, as well as an array of radomes on the southern end of the outpost that appears similar to, if smaller than, the one on Fiery Cross Reef.

Mischief Reef

This year construction was undertaken on buildings covering 17 acres, or 68,500 square meters, of Mischief Reef. Like at Fiery Cross and Subi, this included underground storage for ammunition and other materiel, the completion of hangars and missile shelters, and new radar and communications arrays.

The new storage tunnels at Mischief were completed over the last several months and have been buried, joining previously-built underground structures to the north.

In addition to previously-identified structures, China has started work on a new radar/communications array on the north side of the outpost.

China has continued construction, though on a smaller scale, at its bases in the Paracel Islands. The most significant of this work in 2017 was at North, Tree, and Triton Islands.

Tree Island

Like North Island, dredging and reclamation work at Tree Island continued as late as mid-2017. In total, China built facilities covering about 1.7 acres, or 6,800 square meters, of the island. These included a new helipad next to the harbor and solar arrays and a pair of wind turbines on the north shore of the island.

North Island

China had earlier tried to connect North Island to neighboring Middle Island, but gave up the project after the land bridge it created was washed out by a storm in October 2016. Earlier this year, it built a retaining wall around the remaining reclaimed land at the southern end of North Island and built a large administrative building on the feature.

Triton Island

Triton Island saw completion of a few buildings this year, including two large radar towers, which are especially important given that Triton is the southwestern-most of the Paracels and the waters around it have been the site of several recent incidents between China and Vietnam, as well as multiple U.S. freedom of navigation operations.

Woody Island

Woody Island is China’s military and administrative headquarters in the South China Sea. Developments at Woody are usually a precursor to those at Fiery Cross, Subi, and Mischief in the Spratlys. There was no substantial new construction at the island this year, but it did see two first-time air deployments that hint at things to come at the three Spratly Island airbases farther south.

First, at the end of October, the Chinese military released images showing People’s Liberation Army Air Force J-11B fighters deployed to Woody Island for exercises. This was the first confirmed deployment of J-11s to Woody. Previous deployments to the island involved the less-advanced People’s Liberation Army Navy J-10, which is what AMTI has used as a basis—perhaps too conservatively—to estimate Chinese power projection capabilities from its South China Sea bases.

Then on November 15, AMTI spotted several large planes that appear to be Y-8 transport aircraft, which in certain configurations are capable of electronic intelligence gathering. AMTI earlier noted that the larger hangars built at each of the Spratly airbases could accommodate Y-8s, suggesting their presence at Woody could be a sign of things to come.