China has been steadily developing its underwater capabilities. Strategic experts have said that with its objective of establishing hegemony over the Indo-Pacific region, Beijing has taken up several projects in the past decade to strengthen its ability in the maritime domain. China considers it a crucial domain to have strategic leverage for enhancing its geopolitical influence and altering the discourse of international politics.
While China has significantly enhanced its underwater capabilities in the South China Sea, its undersea platforms are now expanding across the broader Indo-Pacific region. This rapid expansion has sparked growing alarm among regional and external stakeholders, who see it as part of China’s broader effort to project power and reshape the Indo-Pacific region’s maritime balance. A closer look at key developments over the past decade reveals a deliberate and multifaceted strategy. The following eight trends illustrate how China is systematically building its underwater dominance:
First, In December 2015, China State Shipbuilding Corp unveiled the “Underwater Great Wall” project, which aimed to establish a network of ships and subsurface sensors capable of real-time detection and tracking of surface and underwater targets.
The project envisaged the deployment of surface ships, sonar systems, underwater security equipment, marine oil and gas exploration equipment, uncrewed underwater equipment and marine electronic equipment to take proactive action against any challenge to its control.
The objectives for this overall ocean-monitoring network include oceanographic research, environmental monitoring, tactical surveillance and surveying the seabed.
Second, in February China unveiled a compact, deep-sea, cable-cutting device, capable of severing the world’s most fortified underwater communication or power lines.
This device can cut lines at depths of up to 4,000m — twice the maximum operational range of existing subsea communication infrastructure — and has been designed specifically for integration with China’s advanced crewed and uncrewed submersible platforms.
Third, China has constructed a 2,000m-deep space station-like facility on the floor of the South China Sea. Last month, six personnel stayed at the station, suggesting it is equipped to support technical staff for sustained operations. This deep-sea outpost could serve as a secure bastion for monitoring and potentially countering foreign naval activity within China’s claimed maritime zone.
Fourth, a report by the War Zone, a defense news and analysis Web site, on April 2 showed that China had developed a new submarine equipped with an advanced X-form rudder — an innovation that improves maneuverability, efficiency and safety while reducing acoustic signatures.
This design is particularly well-suited for operations in littoral environments such as the contested South China Sea. The report is especially significant for India, as it indicates that this new Chinese submarine, along with a Hangor II-class submarine, is being built for Pakistan.
Fifth, over the past four years, Chinese spy vessels disguised as research survey ships have increasingly entered the Indian Ocean. Last year alone, four such “survey” ships were present during India’s missile testing period. Notably, China’s most advanced survey vessel, Xiang Yang Hong-3, was positioned in the Bay of Bengal at the time of one such test. These ships are believed to be deployed primarily for intelligence-gathering purposes.
These survey vessels are capable of collecting seabed mapping data, recording hydrological information to analyze the undersea environment, gathering intelligence on subsea cables and capturing telemetry data from missile tests.
Sixth, while China possesses nuclear-powered and robust diesel-electric submarines, it is now focusing on developing noiseless, nuclear-powered submarines with longer endurance, and since 2015, has been developing the Shang-class (Type 093B) nuclear-powered attack submarines.
The advanced Shang-class submarine features enhanced speed, reduced acoustic signatures and a new vertical launch system. The US Department of Defense estimates that China is expected to complete construction of the Type 093B guided-missile nuclear attack submarine by the end of this year — a new Shang-class variant that would significantly boost the Chinese People’s Liberation Army’s anti-surface warfare capabilities and covert land-attack potential.
Seventh, China has also accelerated the development and production of underwater drones, or uncrewed underwater vehicles (UUVs).
These include a range of advanced prototypes, such as the Zhishui-3 UUV with dual-tail propellers and dual cross-tunnel thrusters, the SPC-3 “robofish” UUV, the Haiyan glider-type UUV, bionic flapping-wing UUVs, flexible double-tail fin UUVs and torpedo-armed variants.
Eighth, China’s largest low-noise research vessel, Dong Feng Hong 3, recently completed a month-long survey of the Ninety East Ridge in the Indian Ocean. This north-to-south underwater mountain range lies near the strategic Sunda and Lombok straits and is considered a critical zone for submarine operations due to its relatively shallow waters and complex topography. The data gathered during the survey is likely to have significant military implications.
The strategic location of the Ninety East Ridge enhances its military significance, as the data collected can help Chinese submarines operate undetected by other naval forces. This is particularly significant for India, given the steady presence of Chinese submarines and vessels in strategically sensitive areas of the Indian Ocean in recent years.
Taken together, these developments indicate that China is intensifying its focus on expanding underwater capabilities — including submarines, torpedoes, naval mines and UUVs. While these platforms are often presented as tools for scientific research, they can readily be deployed for military use to advance China’s broader geopolitical objectives.
Security experts warn that future underwater conflict might not be limited to naval encounters, but could also involve attacks on critical undersea infrastructure such as fiber-optic cables, power lines and deep-sea gas pipelines.
Undersea cables form the backbone of global connectivity, supporting international Internet traffic, financial transactions and diplomatic communications. Incidents of cable damage have occurred repeatedly in recent years.
Recent cases of cable disruptions near Taiwan and in northern Europe have highlighted these risks, while Vietnam previously experienced major outages due to damaged cables. Of particular concern is China’s development of a device reportedly capable of severing even the world’s most secure subsea cables.
This emerging threat adds a new dimension to regional security — particularly as information warfare and cognitive operations are becoming more critical.
In response, Indo-Pacific region stakeholders committed to regional stability must adopt a robust, multi-pronged strategy that combines detection, tracking and neutralization capabilities to protect underwater cables and pipelines in the region.
S.D. Pradhan is a former deputy national security adviser for the Indian government.
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