Bombay Reef is located at the southeastern edge of the Paracel Islands and, like the rest of the chain, has been administered by China since 1974. But until this summer, the only artificial structure on the mostly-submerged reef was a decades-old lighthouse on its western side. The closest Chinese outposts are Lincoln Island 39 nautical miles to the northeast, Woody Island 47 nautical miles to the north, Duncan Island 50 nautical miles to the northwest, and Triton Island 75 nautical miles to the west.

The new platform first appeared at the reef in satellite imagery dated July 7, 2018; it was not present in earlier shots from April. It measures approximately 90 feet (27 meters) long and 40 feet (12 meters) wide and is raised some distance above the water. The structure is topped by a radome measuring roughly 20 feet (6 meters) in diameter and an array of solar panels covering more than 1300 square feet (124 meters). The superstructure hides any other facilities or equipment that the platform may contain.

It is difficult to definitively identify the structure’s use from imagery, but some explanations seem more likely than others. One non-military option could be that it serves as a navigational aid for ships transiting near the Paracels. But the platform appears to be unusually large and sophisticated for a function that could likely be served by a smaller buoy or series of buoys. That would also seem redundant, given that Bombay Reef already has a lighthouse to serve as a navigational aid.

The more likely possibilities, given Bombay Reef’s strategic location, are military in nature.  The reef is directly adjacent to the major shipping lanes that run between the Paracels and the Spratly Islands to the south, making it an attractive location for a sensor array to extend Chinese radar or signals intelligence collection over that important sea lane. The radome is relatively small, especially compared to large sensor arrays built on nearby Woody Island or on China’s major bases in the Spratly Islands, so its capabilities are also likely modest. Power supply is presumably a limiting factor. Bombay Reef does not host a base or any power generation facilities, so the platform must be self-sufficient. The solar panels lining its top may be its only source of electricity, or they could augment a generator in the facilities under the superstructure. 

With China’s rapid buildup of capabilities in the Paracels and Spratlys, the only probable gaps in its domain awareness over the South China Sea are in the northeast around Scarborough Shoal and, to a lesser extent, the waters between the Spratlys and Paracels. Any extension of those capabilities to the south and east from Bombay Reef would bring China closer to its goal of monitoring and projecting power across the entire waterway.

Additionally, the rapid deployment of the platform and its small environmental footprint stands in stark contrast to the intensive process of dredging and reclamation that marked China’s expansion of its Spratly outposts in recent years. If the structure does house a sensor array, it would show that Beijing is capable of quickly establishing a permanent facility to extend its domain awareness around a disputed feature without the environmental destruction and reputational damage that accompanied the earlier island building campaign. This kind of quick, low-impact construction could be replicated in other areas like Scarborough Shoal, control of which China seized from the Philippines in 2012. The Philippines and the United States have been worried that China would build a permanent outpost at Scarborough, and the U.S. government reportedly deterred such a plan in early 2016. But compared to dredging and reclamation, the installation of a modest platform would be harder to prevent at the time and more difficult to rally international condemnation against after the fact.

Recent Analysis
Duterte’s Anti-West Swagger: Personal, But Not Necessarily Policy by Lucio Blanco Pitlo III

China’s Reach Has Grown; So Should the Island Chains by Wilson VornDick

Manila Quietly Pivots Back to the United States by Richard Javad Heydarian

How Southeast Asians Really Perceive the Quadrilateral Security Dialogue by Huong Le Thu