Is India planning to install undersea surveillance sensors in the Bay of Bengal? It is a question that has animated discussions in maritime circles recently. A recent report in the Indian media suggests New Delhi is planning to undertake joint projects with Japan and the United States for the defense of its littoral spaces, including one for the installation of a sound surveillance sensors (SOSUS) chain in India’s near seas. In an article for a Indian defence magazine in April this year, Prasun Sengupta, a well-known analyst and commentator, surmises that New Delhi is considering Japanese assistance in the construction of an undersea network of seabed-based sensors stretching from the tip of Sumatra right up to Indira Point in the Bay of Bengal to prevent Chinese submarines from approaching Indian exclusive economic zone. According to Sengupta, besides providing funds for the upgrading of naval air bases and construction of new electronic/signals intelligence stations along the Andaman and Nicobar chain of islands, Tokyo plans to finance an undersea optical fiber cable from Chennai to Port Blair. Once completed, this network is likely to be integrated with the existing US-Japan “Fish Hook” SOSUS network meant specifically to monitor People’s Liberation Army-Navy (PLAN) submarine activity in the South China Sea and the Indian Ocean Rim.

The starting point for this collaboration is supposed to have been Prime Minister Narendra Modi’s visit to Washington last year, when India and the United States agreed to intensify cooperation in maritime security. New Delhi is said to have decided to move forward with its plans to strengthen its near-seas defenses after ASEAN defence ministers at the ASEAN Defense Ministers Meeting-Plus gathering in Lankawi, Malaysia, in March collectively stated their desire for India to play a security role beyond the Indian Ocean.

There is no official confirmation of these developments. However, it is entirely possible China’s anti-access/area denial (A2/AD) plans in Southeast Asia may have served as a trigger for an Indian response in the Bay of Bengal. In an article last month, Lyle Goldstein, a well known China specialist, claimed Beijing was in the process of creating an undersea “Great Wall” in the South China Sea by establishing an array of ocean-floor acoustic sensors to detect US submarines. China’s hydrophone system is reportedly modeled on the US Navy’s SOSUS, meant originally to track Soviet submarines in the mid-1950s. Reports that the PLAN is on the verge of operationalising its sensor chain may have prompted New Delhi to pursue an undersea sensor project in the South Asian littoral.

The more interesting venture, from an Indian perspective, is between Japan and the United States in the wider Pacific. Since the early 2000s, when PLAN submarine patrols are supposed to have turned aggressive, the US Navy and the Japan Maritime Self Defense Force (JMSDF) began setting up a chain of fixed arrays to monitor the movement of Chinese submarines in the East China Sea and South China Sea. This resulted in the establishment of the “Fish Hook Undersea Defense Line” in early 2005, stretching from Japan to Southeast Asia with key nodes at Okinawa, Guam, and Taiwan. The system reportedly consists of two separate networks of hydrophones, one stretching from Okinawa to southern Kyushu, and the other from Okinawa to Taiwan.

In July 2013, Beijing claimed that the United States and Japan had established “very large underwater monitoring systems” at the northern and southern ends of Taiwan. One supposedly stretched from Yonaguni to the Senkaku Islands, while the other covered the Bashi Channel down to the Philippines. In addition, Chinese analysts contended, large numbers of hydrophones had been installed “in Chinese waters” close to China’s submarine bases in Qingdao, Xiaopingdao, and Yulin on Hainan Island, even though it wasn’t fully clear if these sensors were all operational.

Fewer doubts remain about the efficacy of an older version of the SOSUS in the northeastern Pacific (off the Tsugaru Strait) and the southwestern Pacific (the Tsushima Strait) that Japan and the United States have jointly managed since the days of the Cold War. Analysts aver that Japan’s experience with working the system for over six decades has provided Japanese engineers and technicians with the proficiency and professionalism to install sea-based sensors in distant littoral spaces, including in the Indian Ocean.

New Delhi, however, would need to consider the implications of operating sensitive equipment with a foreign partner– especially the sharing of critical sensor data. In the case of the joint Japan-US SOSUS, for instance, while the JMSDF and US Navy personnel jointly manage the JMSDF Oceanographic Observation Centre in Okinawa, all the information is available to the US Pacific Command,as the facility is under the operational control of the US Navy. Needless to say, there are concerns that India may be required to provide its foreign collaborators with a level of informational access with which the Indian navy may not be too comfortable.

Some observers worry that placing undersea sensors around the Andaman and Nicobar islands may ultimately result in deployment of other A2/AD tools that China might find provocative. Japan’s activation of a coastal surveillance unit on Yonaguni Island, only 67 miles from the east coast of Taiwan, has been widely perceived to be an A2/AD measure. Reports suggest that Japan’s far-flung islands may soon see the placement of mobile anti-ship missile batteries and air-defense systems to bolster A2/AD capabilities.

Against the backdrop of a recent logistical agreement with the United States, and with other foundational pacts like the Communication Interoperability and Security Memorandum Agreement and Basic Exchange and Cooperation Agreement for Geo-Spatial Cooperation in the pipeline, there are concerns that the establishment of an undersea sensor chain around the Andaman and Nicobar islands might be a precursor to the placement of area-denial weapons — a move that Beijing would deem “escalatory.”

Inadequate return on investment constitutes another source of worry. The setting up of a listening array, experts aver, goes well beyond the placement of hydrophones on the seabed. A sound surveillance system requires steady economic and human investment, with the careful cultivation of an entire cadre of specialists able to interpret the array’s data output. The United States and Japan invested in their system for years before it began producing results. India could seek Japanese assistance in installing a SOSUS but could take years on training specialists and refining the related technologies.

Moreover, undersea sensors produce enormous quantities of raw data that require a dedicated system to sift and sort through. Over the years, the task of organising the data collected has become increasingly unviable. The lack of resources to manage data-collection facilities has led navies to consider a proposal to treat the data as a marketable commodity, by sharing it with environmental scientists and civilian agencies for a price. In order to allow the access of data in real-time,however, the hydrophones have had to be connected online, therebyraising concerns about the possible misuse of data.

Despite such worries, an Indian sound sensor array in the Indian Ocean could prove invaluable. For a country that has a major anti-submarine warfare handicap and a lack of operational submarines, an undersea sensor would be a god-send. India has so far not made any major investments in improving its sub-hunting capabilities. If it can install a deterrence system and operate it with a degree of competence, it could retain its strategic primacy in the Indian Ocean.

This commentary originally appeared in Asia Maritime Transparency Initiative.