China is closing a South China Sea surveillance gap with a new radar made to spot stealth aircraft, satellite images suggest

• China looks to be building a new radar system purported to have counter-stealth capabilities, analysts found.
• Satellite images appear to show a SIAR system on Triton Island in the South China Sea.

China appears to be closing surveillance gaps in the South China Sea with the construction of a new radar said to have counter-stealth capabilities on Triton Island, new satellite images show.

This project, especially if the radar functions as advertised, could complicate US operations in the tense and contested region.

Chatham House's John Pollack and Damien Symon reported on new satellite images of Triton Island, part of the Paracels and home to a Chinese military base, earlier this month. The report called attention to the expansion of China's military installations on the island between August 2022 and September of this year, including a new radar system.

Business Insider obtained copies of the satellite images, collected by Maxar, courtesy of Chatham House.

In the photos is what appears to be a synthetic impulse and aperture radar octagonal in structure and purportedly technology able to detect stealth aircraft. China previously built a SIAR system on Subi Reef in the Spratly Islands, further south in the South China Sea and west of the Philippines.

Chatham House noted that once the SIAR system is finished, it'll add to China's larger surveillance and reconnaissance network in the South China Sea by providing overlapping coverage stretching from Hainan Island on the northernmost edge of the strategic waterway to the Spratlys in the south.

Along with SIAR, "China has built dozens of different types of radars across the Spratlys and Paracels over the last 10 years," Gregory Poling, director of the Southeast Asia Program and Asia Maritime Transparency Initiative at the Center for Strategic and International Studies, told Business Insider.

"This is an iteration on a long-term Chinese strategy to dominate the sensor space in the South China Sea," he said.

Last fall, the Pentagon documented growth in China's intelligence-gathering capabilities in the South China Sea, especially at the Spratlys.

While Beijing has stated the main goals of these projects are to improve marine research, safety of navigation efforts in the area, and conditions for personnel stationed at these outposts, the Pentagon said that the effort also "improves the PRC's ability to detect and challenge activities by rival claimants or third parties and widens the range of response options available to Beijing."

China says the SIAR system can track stealth aircraft by operating at a lower frequency. As J. Michael Dahm, a senior resident fellow for Aerospace and China Studies at the Mitchell Institute, wrote in a 2020 report, SIAR is a "unique, circular VHF-band radar array" that's "purposed to have significant counter-stealth capabilities."

If true, that creates potential challenges.

Stealth aircraft are specifically designed with low-observable features to significantly reduce the size of their radar signatures, making them harder to detect and allowing them to penetrate enemy air defenses.

There's a lot unknown about how SIAR works, Dahm told BI, including its specific operating frequency, waveform characteristics, and power emitted. Similarly unclear is how SIAR would affect individual stealth aircraft and how vulnerable those platforms would be to SIAR. He said Chinese scientists who designed the SIAR system claim it can track aircraft such as the B-2 Spirit bomber and fifth-generation F-22 Raptor and F-35 Lightning II fighter jets.

Similar assertions about Chinese detection capabilities have been made previously, but the claims remain unproven. That China appears to be taking steps to construct SIAR in the South China Sea is, however, indicative of the systems having at least some surveillance value.

China likely aims to create "these dense networks of overlapping radar coverage as a way to constrain US operations and funnel the US into operating into areas where the Chinese can array different defenses," Dahm said. Those defenses could be electronic warfare capabilities, surface-to-air missiles, and more.

Dahm said that this is just the latest example of such efforts by China, which has long had the goal of countering and attacking enemy stealth aircraft dating back to observations of how US forces operated during the 1991 Gulf War, in which the stealth F-117 Nighthawk played an important role.

As part of China's massive military buildup and modernization efforts, it has increasingly emhasized advanced technologies for reconnaissance and information warfare.

Earlier this week, the US Air Force Secretary said that the US and China were locked in "a race for technological superiority" rather than a "classic arms race," with a focus on advanced satellites, battle management systems to effectively integrate and control combat assets, and artificial intelligence.