Operating covertly from the depths of the ocean and striking with nuclear weapons is the leitmotif of Ship Submersible Ballistic Nuclear or SSBN submarines. Such capability was demonstrated by India on 14 October this year in the firing of the nuclear-capable missile, Sagarika/K-15, from its first SSBN, the INS Arihant. The submarine was launched in July 2009, with sea trials commencing in December 2014, and was commissioned into the Indian Navy in August 2016. It undertook its first deterrence patrol in 2018, soon after the K-15 missile was first test-fired from the submarine.
The latest missile firing certainly marks another milestone in India’s quest to strengthen its nuclear triad’s crucial sea leg, which is represented by the SSBN. It is considered the most survivable element of the triad in contrast to land and aircraft-based nuclear weapons as they cannot be anywhere near the SSBN capability to remain hidden.
The Arihant is, in many ways, only the harbinger of progress on a long journey that will stretch up to the late 2020s when India will have four SSBNs, probably considered the ideal number that will meet the minimum operational commitments catering for long-term maintenance and unforeseen incidents. The Arihant, in its short life till now, reportedly experienced a mishap in 2018 due to human error that flooded its propulsion chamber and took nearly a year to repair.
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The nuclear triad
The range of the Sagarika missiles is limited and should prove useful against the southern parts of Pakistan. Against China, it would be a risky proposition, though not an impossible one, to hide in the depths of the South China Sea during a probable India-China conflict. Nuclear coverage of Pakistan would then be taken care of by the land and air legs of the triad. But this problem should be resolved when the next SSBNs with the K4 missile range of 3,500 km are deployed and major parts of China can be covered from the Bay of Bengal.
The INS Arighat, the second SSBN, was launched in 2017 and is currently undergoing sea trials. The expected time for commissioning is not known and it may be fully operational after a couple of years. Two tests of the K4 missile were conducted from a submerged pontoon in January 2020. Production activities are also ongoing on two more SSBNs that could perhaps achieve operational status by the late 2020s. At which point, it would be reasonable to assume that India’s nuclear weapon programmme will have reached its planned level of ‘Credible Minimium Deterrence’ (CMD). However, even though considerable indigenisation may have been achieved, disruptions to the progress of submarine-launched ballistic missile (SLBM) and SSBN production due to the Russia-Ukraine War and US-China technological decoupling are wild cards.
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Credible minimum deterrence
The contribution and key role of SLBMs in India’s Credible Minimum Deterrence were acknowledged in the defence ministry statement issued after the 14 October 2022 firing: “The successful user training launch of the SLBM by INS Arihant is significant to prove crew competency and validate the SSBN programme, a key element of India’s nuclear deterrence capability. A robust, survivable and assured retaliatory capability is in keeping with India’s policy to have ‘Credible Minimum Deterrence’ that underpins its ‘No First Use’ commitment.”
The CMD capability, however, is an elastic concept that must be constantly sensitive to any change in the adversaries’ capabilities that threatens assured retaliatory capability. Primarily, the challenge for India is about maintaining and projecting the capability of being able to survive the first strike from China or Pakistan and strike back in a manner described in its nuclear doctrine as ‘Nuclear retaliation to a first strike will be massive and designed to inflict unacceptable damage’. This formulation has been criticised for disproportionality and for not catering to the probability of initial use of lower-yield weapons in small numbers.
The criticism is perhaps justified, though it can be argued that ‘massive’ and ‘unacceptable damage’ are both elastic terms subject to varied interpretations. However, there is merit in the argument for making changes in what was originally proposed in the draft Nuclear Doctrine by the National Security Advisory Board (NSAB) headed by K Subrahmanyam in 1999, which preferred the formulation—“punitive retaliation to cause unacceptable damage”. Be that as it may, one would expect India’s nuclear capability planning to be already looking at the changes that would be warranted in the triad after the four SSBNs become operational.
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The challenges now
Currently, the heavy lifting of the CMD is being done by the land-based missiles of the Agni series, which are complemented by the aircraft-based leg. The question is, how should India visualise the composition mix in its triad after the four SSBNs are operational? For sure, arriving at an answer to this question is challenging indeed, considering the pace of change in technology, the growing capabilities of our adversaries, including Ballistic Missile Defence, and our ability to protect the nuclear command and control system. Though the SSBN can hide deep in the oceans, its unbroken communications channel with the controlling civilian authority is its Achilles heel. This is something that can be severed or interfered with by adversarial powers. It is, therefore, nearly a given that India is unlikely to put all its nuclear eggs in the SSBN basket as done by France and the UK.
Also, India may wish to leverage its continental expanse and deploy its land-based missiles in a dispersed manner. The question that remains would be whether India could do without an aircraft-based nuclear leg and move to a dyadic configuration that remains minimum and credible. Going forward on this track will be an issue that Indian strategic planners will have to resolve while sticking doctrinally to assets that have greater chances of survival.
To sum up, the successful launch of a missile from the Arihant while being a decisive marker of India’s progress in CMD capabilities also signals the complexities of challenges that lie ahead in our nuclear deterrence domain of the unknowable future.
Lt Gen (Dr) Prakash Menon (retd) is Director, Strategic Studies Programme, Takshashila Institution; former military adviser, National Security Council Secretariat. He tweets @prakashmenon51. Views are personal.