Above the surface, a fleet of ships can be counted, photographed and tracked in almost real time. Under water, however, the rules change: the target disappears from sight, the sound is deformed and each contact can be a valid clue or a false alarm. For this reason, anti-submarine warfare remains one of the most demanding tasks of any Navy. China knows this well and is expanding its response to monitor a space where the size of its forces alone is not enough.
A plane enters the scene. The response that China has begun to show from the air is an improved variant of its Y-9 anti-submarine aircraft, now seen for the first time in maneuvers. The aircraft had appeared publicly at the parade on September 3, 2025, but the new official images allow external modifications to be seen in its detection systems. According to military analyst Zhang Junshe, quoted by Global Timesits incorporation into these exercises indicates the beginning of operational training and the acquisition of initial search and attack capabilities.
The difficult part is below. An official evaluation by the US Department of Defense allows us to place the progress of the Y-9 within a gap that China would still be trying to close. Its 2024 report stated that the Chinese Navy was improving its anti-submarine means, but still lacked a robust deep-water capability. In March 2026, scholar Andrew Erickson described an unequal situation, although he made it clear that his conclusions were personal.
According to the expert, China is developing a layered detection architecture within the first island chain, but its capabilities remain more limited beyond it. There, the smallest number of deployed sensors, limited maritime patrol aviation and logistical restrictions weigh in. That does not make these evaluations neutral diagnoses: they come from the United States, the power that tries to preserve its submarine advantage against China.
The next obstacle. Zhang points out that the South China Sea reaches depths of more than 1,000 meters in some areas and has more complex conditions than the East China and Yellow Seas, which makes it difficult to locate submarines. In addition, temperature, salinity, currents and underwater relief modify the propagation of sound. This requires knowing the environment precisely to correctly interpret the information collected by the acoustic systems.
A network, not a single plane. Beijing is not entrusting this entire task to Y-9. A Reuters investigation published earlier this year documented an extensive operation supported by oceanographic vessels, hundreds of sensors, buoys and arrays installed underwater. Separately, Erickson describes a Chinese architecture that integrates space, air, coastal, surface and underwater assets, as well as unmanned vehicles. The new plane represents the aerial and mobile component of that broader effort to understand and monitor what happens under the sea.
The most visible change appears under the nose. According to Zhang, the images show what appears to be a new active phased array radar, with broader coverage, a longer sweep and a greater detection distance than the version presented in 2025. That does not mean directly finding a submerged submarine from the air, but it does mean expanding maritime surveillance and delimiting areas of interest. The more the search area is reduced, the easier it is to then target systems specifically designed to locate underwater targets.
Listen and confirm. Once the area is delimited, the Y-9 can deploy up to a hundred sonobuoys of different types, housed on both sides of the fuselage. These form a listening network capable of covering tens of kilometers and collecting signals from submerged targets. In the tail, what appears to be a new magnetic anomaly detector looks for small alterations associated with a large metallic mass. Its smaller size would reduce the magnetic interference of the structure itself, facilitate maintenance and extend the detection distance.
Beyond what it detects. The Y-9 aims to improve compared to the Y-8 in range, combat radius, takeoff weight and autonomy. In the maneuvers, in addition, the crews operated without a script or fixed tactics, with electromagnetic interference, simulated breakdowns and coordination with other units, within training aimed at improving their search and attack capacity day and night. None of this makes the ocean transparent, but it does show where Beijing is concentrating its efforts.
Images | PLA
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