Military & Aerospace

Bay of Bengal: The Emerging Undersea Battlefield and the Concomitant ASW Challenges
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Issue Vol. 35.4 Oct-Dec 2020 | Date : 10 Jan , 2021

Maps of Bay of Bengal –Physical and Political

Bay of Bengal, a 2,600,000 sq km water body, NE of Indian Ocean, is the largest water body called a “bay” in the world. It has seven basin countries, Bangladesh, India, Myanmar, Indonesia, Sri Lanka, Thailand and Malaysia and two archipelagos, the Andaman & Nicobar island group of India and the much smaller Mergui islands of Myanmar. While always of economical significance for the basin countries, the Bay of Bengal has recently acquired immense geo-strategic implications, with extra-regional consequences. The single major factor being the Chinese Belt and Road Initiative (BRI) and their global economic and military aspirations. The response of the free world to this Chinese beligerence has been multifaceted including formation of the Quad, and other military and quasimilitary treaties and alliances. The annual ‘Excercise Malabar’, a bilateral Indo-US Naval excersise, now is a multi national event with participation of the navies of Bangladesh, Thailand, Singapore, Japan and even Australia. The war game has shifted from the Malabar coast off Kochi, to the Bay of Bengal.

The Bay of Bengal has historically and primarily been used for sea trade and commerce. The Chola dynasty of Southern India, one of the longest ruling dynasties in the world (3 BC to 13 AD) was at its peak during the period 9th to 12th Century and referred to the bay as the ‘Chola lake’. This was followed by the Portuguese in the 16th century, and finally the British. The Maritime Silk Route, established by the Chola dynasty, during the period 2nd Century BC to 1 AD, connected China, SE Asia, the Indian subcontinent and extended right up to Arabian Peninsula, Somalia and and Egypt.  Despite its association with China in recent centuries, the Maritime Silk Road was primarily established and operated by Austronesian sailors in Southeast Asia, Tamil merchants in India and Southeast Asia, Greco-Roman merchants in East Africa, India, Ceylon and Indochina,  and by Persian and Arab traders in the Arabian Sea and beyond.

During the last 50 odd years, however , there has been a gradual yet perceivable shift; the hitherto predominantly commercial and regional essence of the Bay of Bengal, now has a positively extra-regional and confrontational geo-strategic flavour. This shift has been almost entirely driven by the Chinese hegemanous designs and their attempts to have a safer, shorter and faster access to the Persian crude, the African raw material and the global markets. Their ‘strategic nightmare’ is partial or complete blockage of the Malacca Strait. Its core geo-strategic and maritime policy, outside the South and North China Sea, therefore, pivots around its need to ‘either dominate or find an alternative to the Malacca bottle neck’.

To achieve this it has embarked on a two pronged strategy; invest in the Belt and Road Initiative (BRI) through alliances with the smaller basin countries, and enhance its naval presence in the Bay of Bengal. Both these developments in our immediate eastern maritime neighbourhood are unacceptable and demand immediate and proportionate intervention. We therefore ought to upgrade our rather generic ‘Look East’ policy to a more focussed Dominate Bay of Bengal’ strategy.

The Emerging Undersea Battlefield

The Indian Navy – PLAN conflict of interest in the Bay of Bengal stems for our need to ‘maintain sea control and ensure unfettered access and freedom to undertake the entire range of maritime, commercial and economical activities /operations’ and PLAN’s objective to ‘deny or dilute our control of the seas’. An Anti Access/Area Denial (A2/AD) strategy, backed by appropriate force structure, should therefore be the pivot of our counter to the PLAN in the Bay of Bengal.

Unlike the US Navy, the current PLAN force structure, does not permit credible force projection external to the South and North China Seas (SCS & NCS). It can, at best, project force and influence events ashore in the South and North China Seas. Its focus in the SCS/NCS will continue to be A2/AD. Therefore, in the Bay of Bengal, while PLAN surface combatants will continue to show their presence and excercise their right to innocent passage and free navigation, its nuclear submarine force will be the key player.

The sea leg of our nuclear triad is in place and poised to grow into the most credible component of our nuclear deterence strategy. It is no security revelation that to counter China, geo-strategically the Bay of Bengal meets all requirements for deterance patrols by our SSBN’s. Therefore, the Indian Navy will counter all extra – regional deployment which may interfere with our control of the Bay of Bengal. The deep, temperate waters and hydrology makes the Bay of Bengal, ideal for submarine operations, including strategic deployment. It is therefore no surprise that all basin countries, excluding Sri Lanka, are now operating submarines. The latest being the ex Indian Navy’s Kilo Class acquired by the Myanmar Navy. The cause of concern for us is not the free usage of the seas for commerce or the legitimate security requirenents of basin countries, but the increased PLAN submarine sighting and deployments in the North Arabian sea and the Bay of Bengal.

The Bay of Bengal is therefore emerging as an underwater battlespace. While submarine deployment by the smaller navies of the basin countries and the adjacent littorals is also on the increase, the presence of PLAN submarines, under the thin veil of the Maritime Silk Route is our primary cause of concern and needs to be addessed immediately and holistically.

Frequent sighting and brazen deployment of Chinese Submarines in the Bay of Bengal, North Arabian Sea and around the island territories of A&N is a ‘Clear and Present Danger’ to our maritime strategic interests. Having recognized this, the Indian navy has embarked on an ASW (Anti-Submarine Warfare) enhancement program which envisages to address all consequent and concomitant challenges to positively influence and dominate the emerging undersea battlespace in the Bay of Bengal.

Holistic Asw Eco System

To establish maritime dominance over our island territories, the Bay of Bengal and the Arabian Seas, we must acquire and display appropriate ASW capability to monitor, detect, track and if the need arises, interdict, all intruding submarines, including Chinese.

A decade ago, our ASW approach and therefore capability, would have probably been best described as ‘ASW Blindness’. Thankfully in the last decade or so, some of this has changed. There have been three significant ASW inductions that indicate that the Navy has initiated a serious ‘look ASW ‘policy. These are the induction of the Boeing P-8 (India) Neptune, MMA (Multi-Mission Maritime Aircraft), induction of the 3500 ton Kamorta Class ASW Corvette and the installation of a Sound Surveillance Sensors (SOSUS) chain in India’s near seas.

However acquiring ASW hardware and system of systems, though essential, is not sufficient. ASW capability has to be an orchestration of three principal components; Technology, in form of appropriate platforms and systems, Concept of Operations (ConOps), with apposite organisations, processes and mindset and Training, which is real-time immersive and collaborative. These three paradigms collectively form the basis for a holistic ASW Eco System.

The need for the ASW Concept of Operations to be Pervasive, Persistent and Precise and ASW Training to be Real Time, Immersive and Collaborative was articulated in an article by the same author published in IDR in early 2017. This article would therefore concentrate on the aspect of Technology and deliberate on three ASW platforms/Systems recently inducted into the Navy; an airborne platform, on surface combatant and one undersea surveillance system.

ASW Technology – Platforms and Systems of Systems

Technology is the first paradigm of ASW capability (the other two, as mentioned above are Concept of Ops and Training). Before any further deliberations on technologies for the emerging ASW calculus, three factors merit consideration. Firstly, technology is essential but not sufficient to develop true ASW capability. Its acquisition ought to be considered as an enable rather than the final goal of our ASW  ‘capability building’ endeavor. Secondly ASW tech-architecture is a ‘system of systems’ and therefore only as strong as the weakest link. Systematically identifying and eliminating the weakest link should be the strategy for technology upgradation/induction. Only such a dynamic approach, based on the ‘theory of constraint’ and ‘critical chain path management’, would ensure that resource allocation is linked to the desired outcome of ‘continuous capability enhancement’ and the appropriate scale and speed of transformation is achieved. Finally, while technology development/ acquisition decisions are strategic in nature, they cannot be divorced from operational and tactical realities and need to keep the user’s operational needs, existing capabilities and available resources in perspective.

Airborne ASW Asset – Boeing P-8 (India) Neptune

The Indian Navy has been operating IL38 (five airframes) and TU 142 (8 airframes) since 1977 and 1988 respectively. Though classified as LRMP aircraft with Anti-Submarine and Anti-Surface capabilities, their ASW capabilities, at least in our waters, have been suboptimal, to say the least While we still operate the recently upgraded IL38’s, the TU142 have been decommissioned in 2019 and are being replaced by the Boeing P8 (I) Neptune, Multi-Mission Maritime Aircraft (MMA).

India has been steadily and systematically increasing its inventory by ordering the initial eight airframes in 2009, four more in 2016 and more recently, another six airframes in 2019. Capable of operating from the A & N islands these aircraft provide India with a truly capable and proven ASW air–asset. The fact that the US and Australian Navy P8’s operated along with the Indian P8 (I)’s during Malabar 2020 and recently an US Navy P8 staged through the A & N islands, establishes the fact that IN is now operating one of the best MMA’s in the world which has been truly been integrated into our Navy and the QUAD’s order of battle (ORBAT).

These assets now provide the IN with the capability to keep large and distant sea areas of the Arabian Sea and Bay of Bengal under surveillance. The ASW weapon and sensor suite is proven and effective against modern submarines, both conventional and nuclear powered. Our inventory is adequate to establish and maintain ‘white sky’, a term used in ASW to indicate constant air surveillance over a submarine probable area. Thus, as far as our requirement for a contemporary airborne ASW asset is concerned, it is done and dusted.

Surface ASW Asset-Kamorta Class Corvette

Indian Navy very recently inducted INS Kavratti, the fourth and final Kamorta class ASW Corvette. An analysis of the program and the capabilities of ship per se, clearly epitomises what ails our indigenous warship building yards, the DRDO’s non adherence to delivery commitment and product performance and to some extent, the flawed decision making of the senior leadership in the MOD and Navy.

Kamorta Class ASW Corvettes. Dubbed as the State of Art, Stealth, ASW Corvette, the Kamorta was the first serious attempt by the Navy to fulfill the long pending need to have a dedicated ASW surface ship, in adequate numbers, to counter the ever increasing threat of silent modern submarines on both the eastern and western sea boards, and island territories. The last dedicated ASW ship inducted were the twelve Petya class ASW Patrol Vessels of Soviet origin, way back in the early 1970’s; a staggering 50 years ago! What was probably envisaged was ‘Petya Class with a helicopter’. What we finally got is a light frigate, poorly armed, exorbitantly priced, with an underwater sensor-suit sensor totally ineffective for the deep waters of the Bay of Bengal, in grossly inadequate numbers and at an exorbitant price. These are serious shortcomings and merit detailed discussions.

    • The Program – Unreal Time and Cost Overruns. Indian Navy felt the need for an ASW Corvette in the late nineties and placed an order with Garden Reach Shipbuilders and Engineers (GRSE), Kolkata in 2005. The fist ship was delivered in 2014 after an unbelievable 19 years! The cost overrun is a humongous 250%, from a sanctioned cost of Rs 2700 crores to Rs 7800 crores. And this does not include the cost of an ASW helicopter, SAM missiles, the variable depth and towed array sonars, among other yet-to-be-fitted systems. If this was not bad enough, the cherry on the cake is that that has been no penalty or punitive action by the MOD or Indian Navy. No surprise that the yard lost out two international customers, the Philippines and Brazilian Navies.
    • The Platform – Too Large & Expensive and Therefore Too Few. Corvettes, by norm (not necessarily ‘by definition’) are the smallest surface combatant or warships capable of ‘independent deployment, of up to 10 to 20 days. They generally carry a medium weight helicopter and are generally in the 500 to 2500 displacement, and less than 100 mts in length. An ASW corvette would have the full suite of ASW weapons and sensors but limited to self defence anti-air and surface sensor and weapon. The reason these ships are ‘hated’ by submariners is that they are too small a vessel to be considered ‘torpedo worthy’ (the submarine discloses its position once a ship is torpedoed) and yet an ASW corvette can be menacing enough for the submarine and jeopardizes its primary mission. The Kamorta class is too large to be referred to as a corvette; it is more of a light frigate. With a crew of 150, a 3300 ton displacement and unit cost of Rs 2000 crores plus, the Kamorta class has lost the inherent edge of a Corvette in the ASW battlespace. With just four ships of this class, produced in 18 years, we can barely meet our existing ASW workload.
    • Out-dated Technology – Engines and Propulsion System. Stealth is the deciding factor in an ASW encounter. The choice of engines, machinery and propulsion in an ASW ship is therefore governed by their radiated noise. The 1950’s Soviet design, 950 ton Petya class ASW vessel, which we inducted in the early 70’s, was the first warship probably the world, to have a CODAG (Combined Diesel and Gas Turbine) propulsion. The reason was simple – Gas Turbines (GT) have a much lesser radiated noise signature than diesel engines and therefore ideally suited for ASW operations. So the vessel operated the more fuel efficient diesel engines during transit and changed over to the more silent GT mode in submarine probable areas. Even today most modern ASW corvettes have CODAG propulsion and the variable pitch propellers have been replaced with the silent Water jet propulsion. Despite IN having operated twelve Petya class since the early 70’s, for over three decades, our latest Kamorta Class ASW corvettes, unfortunately still have CODAD propulsion and variable pitch propellers.
    • Promised Indigenous Content – The Missing Integrated Helicopter, Self Defence SAM and Incomplete Underwater Sensor Suite. The four Kamorta Class Corvettes do not have an Integrated ASW helicopter, a point defence short range SAM and the variable depth and towed array sonars. There is no ASW helicopter onboard since the indigenous ALH program has not fructified. Without the ASW helicopter the Kamorta class it is not an open sea corvette but a brown water patrol vessel, very akin to a Petya of the 1970’s. It is doubtful if the soon to be inducted MH 60 R Sea Hawk, with a basic weight of 7000kgs, can be accommodated in the hanger of the Kamorta Class. Secondly, the missing SAM preludes’ its deployment in any maritime scenario with an air threat. Finally, the missing Variable Depth and Towed Array sonars, makes the vessel incapable of detecting any submarine operating deep in the Bay of Bengal. The existing medium frequency hull mounted array is primarily an active sonar with limited passive capabilities. It is therefore optimized to detect submarines operating within or close to the surface layer. In the Bay of Bengal a strong surface duct exists up to 60 mts, followed by an isothermal up to around 300 mts. Further a predominant SOFAR channel exists beyond 300 meters. For such a hydrology, a Variable Depth Sonar (VDS) and a Towed Array Sonar (TAS) are required. These crucial under water sensor capabilities are not available because DRDO ‘promised’ to provide these systems within the appropriate time frame but failed to deliver them even after the 10 to 12 year delayed delivery schedule of the ship.

Therefore, notwithstanding the hype around the Kamorta Class Indigenous ASW Corvette, Indian Navy does not possess a suitable surface combatant to address the growing threat of Chinese submarines in the Bay of Bengal. The irony of the situation is that there are no penalties and no heads will ever roll in these Defence PSU’, ship yard, or R & D organisations, and the MOD which again insist that the Navy designs and order platforms and systems from indigenous government organisations, based on their ‘promises’ rather that ‘past performance’. It is sincerely hoped that these major lacunae in the program definition and delivery as well as the platform design and weapon/ equipt fit, will be addressed and mitigated in the follow-on ASW Corvette programs

Undersea ASW Asset – The Sound Surveillance Sensors (SOSUS) Chain

As per a recent article in a leading defence magazine, by a well-known analyst and commentator, India 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’. The article continues to state that ‘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 Fish Hook Undersea defence Line, established in 2005, stretches from Okinawa to southern Kyushu and Okinawa to Taiwan, with nodes at Okinawa, Guam and Taiwan.

While there is no official confirmation of these developments, the Indian PM recently inaugurated a Japanese aided undersea optical fibre cable from Chennai to Port Blair. It is entirely possible that China’s anti-access/area denial (A2/AD) plans in Southeast Asia and the fact that PLAN has established and an undersea “Great Wall” in the South China Sea by establishing an array of ocean-floor acoustic sensors to detect US and Japanese, propelled New Delhi to pursue an undersea sensor project in the South Asian littoral.

The SOSUS in general and the Indian strategic context in particular, comes with their own set of challenges. Some of these are discussed in the succeeding paragraphs.

Concept. Developed in the 1950’s by the US Navy against Soviet submarines, the SOSUS is a long-range fixed passive detection system. The SOSUS deploys a linear array of hydrophones, placed on slopes or mounts within the sound channel. It primarily exploits the deep sound channel or SOFAR, within which low frequency sound travels to extremely long distances. The azimuth beam forming and triangulation for position approximation are processed ashore. The target information is then shared, in real time, with an air or surface asset in the vicinity; which then undertake the subsequent tasks of classification, tracking and final interdiction. The SOSUS therefore, is a detection system, not a tracking or classification system. When augmented by a mobile ‘Surveillance Towed Array Sonar System (SURTAS) or any other Tower Array Sensor System (TASS), the SOSUS it is referred to as an ‘Integrated Underwater Surveillance System’, IUSS.

Sharing of Critical Sensor Data. New Delhi, however, would need to consider the implications of operating sensitive equipment with a foreign partner– especially the sharing of critical sensor data. There are also 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. This is more so since India has a mix of Indigenous, Russian and Wester origin weapons and sensors. The US too had similar concerns regarding their technology and data/information security.

Indo-US Strategic Alliances. The three Indo-US strategic foundational pacts, The Logistical Agreement’, The ‘Communication Interoperability and Security Memorandum Agreement’ and ‘Basic Exchange and Cooperation Agreement for Geo-Spatial Cooperation’ are now in place. With these agreements, the Intel sharing and data/information security concerns have been addressed. We can now consolidate and enhance the alliance to meet the emerging geo strategic calculus of the Indo–Pacific and the Bay of Bengal region.

Return on investment. 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 US/ Japanese assistance in installing a SOSUS but could take years on training specialists and refining the related technologies.

Data Collection, Mining and Security Challenges. Undersea sensors produce enormous quantities of raw data that require a dedicated system to sift and sort through. Over the years, the task of organizing 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, thereby raising concerns about the possible misuse of data.

Despite such worries, an Indian sound sensor array in the Indian Ocean, once operationalised could prove invaluable in monitoring and neutralise (when required) submarines attempting to sneak into the Bay of Bengal. For a country, which has a major anti-submarine warfare handicap and a lack of operational submarines, an undersea sensor, would be a godsend.

The establishment of the undersea sensor chain around the A&N islands would be a precursor to the placement of area-denial weapons on the shore and islands – a move that would adversely affect Beijing’s hegemonic designs in the Bay of Bengal. India has so far made very limited 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 edge in the Indian Ocean.


While always of economical and commercial significance for the basin countries, the Bay of Bengal has recently acquired immence geo-strategic implications, with extra-regional consequences. The major factor of this transformation is China’s Belt and Road Initiative (BRI) and their global economic and military aspirations. To ensue their ininterupted access to the Persian crude, the African raw material and global markets, their core geo-strategic and maritime policy, outside the South and North China Sea, pivots around their need to ‘either dominate or find an alternative to the Malacca bottle neck’.

The deep, temperate waters and hydrology of the Bay of Bengal are a ‘submariners delight’. It is no surprise that, other than Sri Lanka, all other basin countries are either operating or are in the process of acquiring submarines. Given PLAN’s limited force projection capability outside the North and South China Sea, its nuclear submarine force will be the key component to enforce sea denial in the Bay of Bengal and North Arabian Sea. The Bay of Bengal therefore has now emerged as the next undersaea battle space. Our generic ‘Look East’ policy now needs to be upgraded to a more focused Dominate Bay of Bengal’ strategy. This can only be achieved by a robust and effective A2/AD capability, with enhanced focus on the Anti Subnarine warfare components.

Amoung the various a A2/AD initiatives, in the Bay of bengal, the three ASW assets aquired/initiated by India are the P8 (I) Neptune MMA from the US, the indigenous Kamorta Class ASW Corvettes and the reported SOSUS system being considered as per open sources. While the Corvette programe may need some course corrections, the other two ASW platforms/ systems are either already in place or progressing as envisaged. When coupled with a clearly thought through ‘Concept of Operations’ and contemporary ‘Training and Learning Philosophy’, these platform/ systems, along with certain other similar emerging technologies being contempelated, the Indian Navy is progressing well to counter the growing Chinese undersea – threat in the Bay of Bengal and the concomitant ASW challenges.

Hitherto when one wanted to enunciate the geo-strategic extent of India, the term ‘Kashmir to Kanyakumari’ was considered adequate and apt. This however changed post the Indo-China standoff of June 2020. Now a more appropriate description of our geo-strategic frontier would probably be ‘Daulat Beg Oldie (DBO) to Indira Point’. While DBO represents our northern most strategic Himalayan outpost, Indira Point defines our southern and eastern most maritime outpost. Given its strategic location, if appropriately augmented, Indira Point could be the “cork to the Malacca bottle neck.”

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The views expressed are of the author and do not necessarily represent the opinions or policies of the Indian Defence Review.

About the Author

Cmde CP Srivastava

is a veteran submariner and the Director, Intellectual Resource and Consulting.

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