China Expands Secret Undersea Intelligence Network in Global Rivalry With the U.S.
A Reuters investigation says Beijing is quietly turning the world’s oceans into a surveillance battlefield by deploying dozens of official “research” ships to map the seafloor for military use. Over the past five years, at least 42 such vessels have been used to place hundreds of sensors and buoys and to carry out detailed bathymetric mapping, with the aim of building a covert underwater sensor network that would help the Chinese military track Western ships and gain an edge in submarine warfare.
One example cited is the research ship Dong Fang Hong 3, whose 2024 to 2025 activity focused on strategic routes between Taiwan and Guam, a key American stronghold in the region. The ship’s operating university said it was conducting “mud tests,” but Reuters’ technical analysis concluded the work was deep military mapping. The report says the pattern shows civilian cover being used to collect pure military intelligence.
Under what China calls the “Transparent Ocean Project,” Beijing has also deployed sensor arrays that detect temperature, salinity and underwater vibrations. Those networks have been placed around India, along key routes to the Strait of Malacca, and even in the Arctic. The U.S. Navy’s director of naval intelligence warned Congress that the data China gathers is vital for improving sonar performance, allowing Beijing to monitor Western submarines and deploy its nuclear fleet more safely. Security officials said, “Every sensor placed on the seabed is another set of eyes for China in the water.”
The report says experts see the scale of the effort as evidence of preparations for future war, while Beijing keeps expanding the network and occasionally shutting down tracking systems, suggesting the real picture may be even larger than what is visible. The Chinese activity comes as the U.S. Navy advances underwater warfare technology, including cooperation between Navy SEAL mini-submarines and underwater drones, while China has also unveiled a 0.3-gram mosquito-shaped spy drone and Taiwan has launched a secure reporting channel aimed directly at Chinese citizens.
