A Chinese research vessel operated covertly in the Bay of Bengal for several days last month, sailing close to Indian waters without broadcasting its location raising fresh concerns about Beijing’s growing strategic presence in the region. The vessel, detected by French satellite intelligence firm Unseenlabs, was found operating around 120 nautical miles off India’s east coast - outside the Exclusive Economic Zone (EEZ) close enough to monitor naval operations and submarine activity. The ship had switched off its Automatic Identification System (AIS), a move commonly used to evade tracking. As reported by The Economic Times, Unseenlabs tracked the vessel during a 16-day survey using satellite-based radio frequency (RF) emissions. Of the 1,897 ships monitored during the period, nearly 9.6 per cent including the Chinese vessel were found operating without AIS signals.
Nearly 1 in 10 ships operating without location signals
Unseenlabs which tracks maritime activity through radio frequency (RF) emissions, monitored 1,897 vessels in the Bay of Bengal during its mission. One Chinese vessel drew particular attention due to the consistency of its RF signature and its prolonged presence near areas of recent Indian naval activity.
“While not broadcasting AIS, its RF signature was consistent and traceable enabling our systems to monitor its movement over several days. We suspect that this prominent Chinese research vessel was likely operating with strategic intent,” the firm stated.
Suspected mission: seafloor mapping, acoustic surveys
The satellite data suggests the vessel was engaged in activities such as seafloor mapping, acoustic environment analysis, and identification of submarine transit corridors. These activities are not uncommon in oceanographic research but defence officials say such data can be dual-use supporting both civilian and military operations.
In particular seafloor data and acoustic profiling are crucial inputs for anti-submarine warfare (ASW), allowing navies to locate, track and hide submarines more effectively. The location near Indian missile testing ranges and the Eastern Naval Command base in Visakhapatnam has added to the suspicion.
Not an isolated incident
This is not the first time a Chinese research vessel has raised concerns in Indian maritime zones:
- In March 2024, the vessel Xiang Yang Hong 01 was detected off the east coast during an Indian Agni-5 missile test.
- In mid-2024, Xiang Yang Hong 03 was observed near a Navy submarine warfare drill.
- In early 2025, Xiang Yang Hong 01 returned to the region and remained anchored for nearly three months near the Andaman and Nicobar Islands, reportedly testing autonomous underwater vehicles (AUVs).
While China maintains that such deployments are part of legitimate marine research, officials in New Delhi increasingly view them as components of a broader intelligence and military mapping campaign across the Indian Ocean Region (IOR).
AIS blackout raises legal and strategic questions
AIS is a globally mandated safety protocol under the International Maritime Organization (IMO) for all ships over 300 tonnes. It allows vessels to broadcast their identity, position and navigation status to others nearby. Disabling AIS near another country’s maritime zones is widely seen as suspicious and while not illegal in international waters, violates transparency norms and can be treated as a security risk.
Although the vessel in question did not enter India’s EEZ, its location just 120 nautical miles from Indian shores gives it line-of-sight access to undersea and acoustic data valuable for both surveillance and combat deployment planning.
India monitoring situation
Indian defence authorities confirmed that the ship was being monitored throughout its time in the region. Officials said the Navy and Coast Guard maintain continuous surveillance of vessels around India’s maritime borders and may take up the issue through diplomatic or security channels.
Vice Admiral Rajesh Pendharkar, head of the Eastern Naval Command has earlier stated that Chinese research ships are denied access to the EEZ without prior clearance and are under ‘continuous observation’ when they enter the wider Indian Ocean Region.
India is also scaling up its maritime domain awareness infrastructure including seabed surveillance networks, coastal radar chains and quad-lateral intelligence sharing with partner countries such as the United States, Japan and Australia.
