International attention has shifted away from developments in the South China Sea during 2017, but China has continued substantial construction activities on its dual-use outposts in the Spratly and Paracel Islands.

The area is fraught with international tension, including territorial disputes with Brunei, Malaysia, the Philippines, Taiwan, and Vietnam, as well as implications for international trade and freedom of navigation and overflight. An estimated $5 trillion in cargo passes through the South China Sea every year by ship. China’s construction in the region raises concerns that it is attempting to exercise hegemony over the eastern Pacific Ocean.

According to the Asia Maritime Transparency Initiative (AMTI), 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,” a recent AMTI report said.

Permanent facilities on which China completed or began work since the start of the year include buildings ranging from underground storage areas and administrative buildings to large radar and sensor arrays. These facilities account for about 72 acres of new real estate at Fiery Cross, Subi, and Mischief reefs in the Spratlys, and North, Tree, and Triton Islands in the Paracels.

Fiery Cross saw the most construction in 2017, with work on buildings covering 27 acres. This activity includes completion of the larger hangars alongside the airstrip, work on large underground structures at the south of the island to house munition, a large communications array at the northeast end of the island, various radar and communications facilities spread around the islet, and hardened shelters for missile platforms at the south end. In the last several months China has constructed what appears to be a high-frequency radar array at the north end of the island.

China appears to be ready to boost its radar and signals intelligence capabilities at Subi Reef.

New storage tunnels at Mischief Reef were completed over the last several months and have been buried, joining previously-built underground structures to the north. China has also 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.