China is racing to make the Western Pacific “transparent” to submarines—pitting its expanding seabed-to-space surveillance web against the stealthiest arm of US sea power.
This month, Defense One reported that China is rapidly advancing its “Transparent Ocean” system, a five-layer seabed-to-space sensor network designed to render the Western Pacific “transparent” to submarine activity. Led by the People’s Liberation Army (PLA), the system combines satellites, unmanned boats, underwater gliders, seabed sensors and a main data center to monitor and track submarines as they move.
The concept was demonstrated during Joint Sea-2025 exercises near Vladivostok, where Chinese and Russian forces conducted anti-submarine warfare drills, sharing hydro-meteorological and air-sea tracks to eliminate concealment for deep-diving submarines.
PLA theorists argue that traditional kill chains are vulnerable to disruption and advocate for a resilient “kill web” architecture that reroutes data and targeting paths instantly. The system’s backbone includes undersea cables and docking hubs, enabling unmanned vehicles to recharge and redeploy without surfacing.
Civil-military fusion efforts have accelerated development, with institutions like Zhejiang University and the China Academy of Sciences contributing to sensor integration and vehicle autonomy.
The strategy poses a deepening challenge to US and allied submarines, particularly in strategic chokepoints such as the South China Sea and Luzon Strait. The PLA’s expanding sensor net could complicate peacetime surveillance and necessitate counter-sensing and counter-unmanned underwater vessel (UUV) doctrines among allied navies.
Artificial intelligence (AI) is poised to play a central role in tying these different systems together into an integrated sensor network. David Stupples mentions in an article this month for The Conversation that AI could fuse data from multiple sources into a coherent picture, work tirelessly, unlike human operators and predict submarine operations by continuous learning, changing anti-submarine operations from reactive to predictive.
Stupples notes that such developments could make the oceans transparent in the mid-2030s, much like how radar made the skies transparent in the early 20th century.
However, these claims face significant caveats. In a Royal United Services Institute (RUSI) article this month, Edward Black and Sidharth Kaushal mention that while Chinese articles, possibly state-approved, tout the effectiveness of such a system as reducing the survivability of enemy submarines to 5%, that would necessitate the presence of multiple, layered, active and passive, interconnected sensors as well as, presumably, a substantial amount of data on target vessel signatures.
Black and Kaushal also point out that while the construction of an “Undersea Great Wall” made up of layers of overlapping sensors in regions like the South China Sea has been a long-term (and state-wide) endeavor, it cannot be concluded from the reports that the required sensors, processing nodes, and undersea communication networks have been developed and tested to the extent required to make such detection probabilities a reality yet.
However, they stress that the messaging behind the pronouncement is clear—the People’s Liberation Army Navy (PLAN) aims to fortify China’s adjacent waters against enemy submarines, extend the range of China’s undersea anti-access/area denial (A2/AD) and restrict adversary freedom of action.
Despite those caveats, the threat US submarines pose to China’s regional ambitions cannot be overstated. In March 2025, the South China Sea Probing Initiative (SCSPI), a Chinese think tank, released a report mentioning that the US Navy conducted an unprecedented number of submarine operations in the South China Sea in 2024.
Those operations were conducted by at least 11 nuclear attack submarines (SSNs), two guided-missile submarines (SSGNs) and one ballistic-missile submarine (SSBN) operating in the region supported by tenders USS Frank Cable and USS Emory S. Land that made frequent port visits to Singapore, Malaysia, Brunei, Japan and South Korea.
The SCSPI report says that the deployment of the USS Minnesota to Guam marked the first permanent forward basing of a Virginia-class attack submarine in the Western Pacific, replacing aging Los Angeles-class boats. It also highlighted a steady rotation of submarines through the region for cruise missions.
Those submarines would likely play a vital role in any US-China conflict over Taiwan. Mike Sweeney notes in a March 2023 Proceedings article that submarines are the US Navy’s most survivable and strategically decisive platforms, offering stealth, firepower and deep penetration into contested areas.
Sweeney stresses that despite limited numbers, they could blind Chinese sensors, strike inland targets and disrupt naval formations. He adds that their operational reach bypasses the need for overseas bases, unlike carrier groups.
US submarines could wreak havoc on a Chinese invasion force. William Toti mentions in a December 2023 Proceedings article that in a simulated Chinese invasion of Taiwan, four US SSNs and one SSGN sunk 53 enemy ships in just two weeks, including two carriers and two amphibious assault ships. Toti mentions that US SSNs, operating in the shallow, noisy waters of the Taiwan Strait, prioritized torpedo attacks over missiles to preserve stealth.
At the same time, US submarines can also threaten China’s undersea nuclear arsenal. In a November 2023 China Maritime Studies Institute (CMSI) report, David Logan mentions that China has already been conducting continuous at-sea patrols with its Type 094 SSBNs, with the South China Sea being an ideal bastion.
In this secure area, its SSBNs could launch their submarine-launched ballistic missiles (SLBMs) to increase survivability and ensure second-strike capability using the JL-3 SLBM that could hit the US mainland when launched from the strategic body of water.
Beyond providing second-strike capability, China’s undersea nuclear arsenal also serves as a backstop for its conventional forces—yet its vulnerability may belie its messaging about a state-of-the-art sensor network.
While an SSBN is considered the ultimate in second-strike capability, it may also be a brittle deterrent. Should an SSBN lose contact with shore-based command, be prevented from launching its SLBMs or be destroyed, it could mean the loss of its entire nuclear armament and an entire leg of China’s nuclear triad, especially when only one SSBN is on patrol.
Shadowing SSBNs carries a huge risk of nuclear escalation, as China could be forced into a use-it-or-lose-it scenario—deciding to launch its SLBMs before its SSBNs could be destroyed by US and allied submarine and anti-submarine forces.
In the end, China’s bid to light up the deep may only sharpen the shadows—turning the contest between sensors and submarines into the defining duel underneath the Pacific.
