India’s Undersea Deterrent
INS Chakra
Image Credit: REUTERS/R Narendra

India’s Undersea Deterrent


In February this year, it was reported that India’s first ballistic missile submarine (SSBN), the indigenously built INS Arihant had successfully completed sea trials, including several weapon release tests. The Arihant is expected to be formally commissioned soon, and is likely to serve in a training and force development role as well as providing a limited deterrence, especially once a new intermediate range submarine launched ballistic missile (SLBM) becomes operational.

Three more ships of the Arihant class with enhanced features are planned, with two already under construction even as a new generation SSBN design is being readied. If the move to create back-up systems such as long-range communication facilities, dedicated hardened bases and support vessels is taken into account, it is clear that India is committed to achieving a nuclear triad, which would be in accordance with its doctrine. However, given the broad design characteristics of the initial Arihant class boats, India will adopt a bastion approach in the Bay of Bengal (BoB) for SSBN patrols. This in turn will provide added impetus for increasing naval force levels in the Andaman & Nicobar (A&N) archipelago. It will also mean that India is unlikely to extend unqualified support to the U.S. interpretation of freedom of navigation on the high seas.

While the weapon release tests mostly referred to launches of the operational K-15 SLBM that has a range capability of 750-1000 kilometers (km) depending on the size of the payload and flight profile, the Arihant’s tubes are also capable of fielding versions of the Nirbhay and Brahmos cruise missiles. The true enabler for the Arihant to carry out a limited deterrence mission vis-à-vis China is, however, the K-4 SLBM, developed by India’s Defence Research and Development Organization (DRDO) with a range capability of 3500 km. The K-4 would allow the Arihant to undertake patrol missions from the Eastern part of the BoB, far from the fulcrum of China’s anti-submarine warfare (ASW) web. The K-4, which underwent its latest test in early March, has a length of 10 meters, a diameter of 1.3 meters, can carry a one ton payload, and fits into the Arihant without any need for modifying the latter. Like the smaller K-15, the K-4 is also capable of boost-glide flight profiles designed to defeat emerging anti-ballistic missile systems. With the availability of satellite updates to remove accumulated errors from its inertial navigation system, the K-4 is claimed to be quite accurate.

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The K-4 will also arm the other Arihant class boats currently under construction. The first of these boats, the INS Aridhaman, which for project purposes is designated S-3 with the Arihant being S-2, is expected to be launched soon. Aridhaman and the two other Arihant class boats that will follow it will be somewhat larger and more advanced than the Arihant. For one, the Arihant’s immediate successors will sport eight launch tubes as compared to the Arihant’s four with each tube capable of carrying either a single K-4 or three K-15 missiles. Due to the increased loadout and size, these follow-on ships will also have an up-rated version of the Arihant’s 90 MWth (thermal) pressurized water reactor (PWR). The Arihant class boats themselves will be followed by a new generation SSBN that will be appreciably larger and will be propelled by either a single unit of a much more powerful reactor or two units of a later version of the existing Arihant class reactor. The first of these new generation SSBNs is designated S-5 and will be launched by the mid-2020s. Incidentally, these boats will be built in parallel with the six new nuclear attack submarines (SSNs) that were given cabinet approval last year.

The S-5 and its successors will also be armed with a new three-stage SLBM that will be able to carry a 2 ton payload consisting of up to four MIRVs out to a distance of more than 6000 km. This “heavy” SLBM, likely called K-6, with a length of 12 meters or so, is meant for the 12-16 launch tubes that will feature on the S-5, enabling it to carry out deterrence patrols from the Southern Indian Ocean.

New Naval Base

To accommodate this expanding fleet, work is underway on a new naval base on India’s Eastern Coast at Rambilli in the state of Andhra Pradesh, called INS Varsha. The new base is specifically designed to host nuclear submarines, both SSBNs and SSNs, and is only 50 km away from the port city of Vishakapatnam that is home to the Ship Building Centre (SBC) that integrates India’s nuclear submarines. This base will likely feature de-gaussing facilities as well as underground submarine pens linked to open water by access tunnels. The onset of a deep diving nuclear submarine fleet has also played a role in India’s Cabinet Committee of Security according final approval to a long pending proposal for the procurement of two deep submergence rescue vessels (DSRVs). The two new DSRVs cleared for procurement from a U.K.-based firm will be hosted by two new submarine tender ships currently under construction at a public shipyard. India last operated a DSRV in 1989 called INS Nistar when it had just started operating its first nuclear boat, a Charlie class SSN leased from the Soviet Union.

For communicating with its emerging nuclear fleet, which already includes the INS Chakra, an Akula 2 leased from Russia, and soon the Arihant, the IN has set up a new very low frequency (VLF) transmitting station at INS Kattabomman near the southern tip of mainland India. INS Kattabomman is an advancement over an existing VLF station located in its vicinity, which was established in the 1980s with U.S. help, in terms of range and data transfer capability, among other aspects. In 2014, extreme low frequency (ELF) transmitters were added, clearly indicative of a need to communicate with deeply submerged submarines.

Although India’s SSN fleet may operate across the Indo-Pacific, the deterrence mission will initially be prosecuted via bastions in the BoB. Owing to the range of the K-4, the general patrol areas of the Arihant class boats fielding this missile will lie in locations such as the Andaman Sea where IN surface and air assets will be able to keep overwatch. Moreover, launches from around the A&N archipelago can traverse azimuths that may be able to avoid China’s future ballistic missile defenses (BMDs) altogether.

While the Arihant will naturally serve as a training platform for crews that will man its successor boats, just as the Chakra has been used to train the Arihant’s crew, like the latter it too will perform direct security missions. The Arihant’s reactor could be considered to be similar to late second generation VM series submarine reactors given acknowledged Russian assistance in this sphere. Such reactors needed refueling every 7-10 years at normal power consumption levels and the core lifetimes are sufficient for up to 5000 hours of journeying. This would be adequate for limited deterrence missions in potential patrol areas. Indeed, as the then IN Chief of Staff, Nirmal Verma stated in 2010, “India’s nuclear triad is there when it is commissioned,” indicating clear intent to mount deterrence patrols using the Arihant.

At the time of the Arihant’s launch in 2009, the outgoing Russian ambassador to India, Vyacheslav Trubinikov, noted that its design was based on the Akula class boats. Now if this were a reference to the Arihant’s level of quietening, it could mean that the boat was quieter than both China’s Shang Class SSNs as well as its Jin Class SSBN’s, if one were to go by the U.S. Office of Naval Intelligence’s 2009 rankings about the degree of stealth exhibited by these boats. In any event, active noise cancellation technologies are likely to find their way into the Arihant’s successors, making them more difficult to detect.

Be that as it may, China’s ASW capabilities are improving and there are suggestions that the Shang Class SSNs may deploy thin-line towed array sonars in the future. Moreover, in recent years, Chinese nuclear attack boats have started showing up with increased frequency in the BoB. At this point in time, India has only one SSN – the INS Chakra – to serve as an escort for the Arihant and that too at the cost of other missions. The Arihant on its own will not be able to outrun a Shang class SSN if it is detected. This means that the Arihant’s initial patrol area must be a bastion in the Eastern BoB, where it can be protected by air and surface assets. Ergo, the added urgency to finally commence the long promised build-up of the A&N islands by the Indian Navy.

To counter the growing number of both surface and sub-surface People’s Liberation Army Navy (PLAN) “contacts” in the vicinity of the A&N archipelago, the Indian Navy has already increased the number of patrols mounted by long-range maritime ASW aircraft like the Boeing P-8I Neptune. But the most pressing need for the Navy is to permanently station ASW assets on the A&N archipelago, itself including new stealthy Kamorta class corvettes, medium range maritime patrol aircraft, ASW helicopters, and other assets. For this purpose, dockyard facilities in the A&N islands are being built, existing runways are being extended, and existing air stations are being given more support facilities. With the status of the “tri-service” A&N command evolving into an Indian Naval Command, the stationing of a small fleet in the archipelago is very much a possibility, provided the Navy continues to receive budgetary support. Since 2002, there has also been a proposal to build a hardened submarine base in the A&N.

The build-up in the A&N and its link to providing protection for future SSBN bastions has another aspect to it. Given that these “bastions” will overlap with India’s exclusive economic zones (EEZs), India may not be very keen to change its opposition to the U.S. Navy’s stance of “right to uninterrupted passage” in coastal waters. While India is rather alarmed by China’s island building activities in the South China Sea, and has lent its support to freedom of navigation in those water, it does not support the U.S. Navy’s specific interpretation of freedom of navigation in coastal waters and is unlikely to change this position given the new realities.

Saurav Jha is a commentator on energy and security affairs. Follow him on Twitter @SJha1618.

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