China's Undersea Great Wall Targets US Sub Supremacy

Seif said newer Shang III and follow-on Type 095 SSGNs, armed with land-attack cruise missiles, pose a multi-faceted threat that increases operational demands on US and allied anti-submarine warfare forces. He cautioned that if China raises detection probabilities in key areas, it could raise operational risk for US forces and complicate intervention in a crisis.

This effort shows China's aim to protect its sea-based nuclear deterrent from US submarine surveillance. The key question is whether China's Blue Ocean Network, South China Sea defenses, and SSN/SSGN upgrades form a strategy to shield SSBNs from US tracking and recalibrate the undersea balance in the Pacific.

The answer may lie not just in more submarines, but in building an undersea battlespace that is no longer opaque to adversaries alone.

Dissecting China's undersea sensor network, Tye Graham and Peter Singer note in an October 2025 Defense One article that it comprises five interconnected layers stretching from the seabed to space.

Graham and Singer mention that the topmost layer is the“Ocean Star Cluster,” a satellite constellation centered on the Guanlan radar altimetry and ocean-profiling light detection and ranging (LIDAR) system, which uses pulsed laser signals to generate high-resolution three-dimensional mapping for wide-area cueing.

Below the Ocean Star Cluster, they say that the“Air-Sea Interface” layer employs smart buoys, wave gliders, and unmanned surface vessels as relays. Beneath that, they observe that“Starry Deep Sea” deploys floats, gliders, and autonomous underwater vehicles, while“Undersea Perspective” incorporates seabed observatories and cabled hubs. Graham and Singer add that the“Deep Blue Brain” integrates and manages data across domains.

In terms of coverage, the Asia Maritime Transparency Initiative (AMTI) mentions that China's Blue Ocean Information Network is concentrated in the northern South China Sea, stretching between Hainan Island's Lingshui County and the Paracel Islands, including Woody Island and Bombay Reef.

AMTI notes that floating and fixed“Ocean E-Stations” have been deployed around Hainan and at Bombay Reef, with platforms positioned to monitor key waterways such as the Qiongzhou Strait.

It also says official plans call for expanding coverage across the rest of the South China Sea, into the East China Sea, and eventually to other ocean areas beyond Chinese territory, with long-term ambitions extending along the Maritime Silk Road and even into polar waters. The main purpose of this sensor network may be to protect China's undersea nuclear arsenal, specifically its SSBNs deployed in a bastion strategy.

In an October 2024 interview, Professor Chi Guocang of the People's Liberation Army Navy (PLAN) Submarine Academy explains that China's undersea nuclear deterrent now rests on achieving“continuous strategic duty,” meaning at least one Type 094 SSBN remains on 24-hour, year-round at-sea readiness capable of executing a nuclear counterattack on supreme command order.

Chi says that China can sustain this posture with six Type 094 SSBNs, arguing that“six is a more reasonable number to ensure that there is enough redundancy to deal with emergencies.”

He further describes a South China Sea“strategic bastion,” where deep waters and layered defenses allow SSBNs to maneuver and hide while maintaining deterrence coverage against major adversaries.

Furthermore, David Logan mentions in a November 2023 China Maritime Studies Institute (CMSI) report that Chinese strategists are explicitly concerned about the ability of US attack submarines to track and potentially destroy China's SSBNs.

Logan cites a Chinese assessment arguing that the US possesses“a sufficient number of nuclear attack submarines to ensure continuous tracking of each Type 094 SSBN on a deterrence patrol in peacetime.”