India’s submarine conundrum: nuclear or conventional? - Broadsword by Ajai Shukla - Strategy. Economics. Defence.

Home Top Ad


Friday 24 September 2021

India’s submarine conundrum: nuclear or conventional?

A debate rages over whether the Indian Navy should be going in for conventional diesel-electric submarines, or AIP vessels or SSNs 

Ajai Shukla

Business Standard, 25th Sept 21


Barely a month after the US troop withdrawal from Afghanistan, America is making a strategic course correction, partnering two other Anglophone countries – Australia and the UK – in launching a new defence alliance in the Asia-Pacific. 


Appearing together on television on September 15, the three countries’ leaders – Joe Biden, Boris Johnson and Scott Morrison – jointly announced an “enhanced trilateral security partnership” named AUKUS (Australia – UK – US).


Signalling that AUKUS meant business, the first announcement by the three leaders was that the UK and US would provide Australia with the classified technology and wherewithal needed to build and operate up to eight nuclear-powered attack submarines (SSNs).


Previously, the US has transferred nuclear submarine technology only to the UK in 1958; Australia will be the second recipient, making it the world’s seventh operator of nuclear submarines after America, Britain, China, France, India and Russia. 


This was a slap on the face to France, since Australia had already chosen Naval Group, the French shipbuilder, to supply 12 conventional, diesel-electric submarines for $90 billion. Now that is cancelled and, instead, Australia will have a fleet of SSNs, based on American and British designs, that can patrol the faraway South China Sea, while remaining interoperable with its AUKUS alliance partners’ submarines.


Adding insult to injury, the decision not to buy Naval Group’s conventional Barracuda submarines came with the implicit conclusion that they lacked the range and capability needed to confront its People’s Liberation Army (Navy), or PLA(N) adversaries. 


Washington’s role in forming AUKUS and in equipping the Royal Australian Navy (RAN) with SSNs is part of America’s strategic attention shift from messy conflicts in West Asia to the growing confrontation with an assertive rival superpower – China.


No longer is US security policy driven by American thirst for West Asian oil supplies. According to data for the year 2020, from “International Energy Statistics,”, the US is now the world’s biggest oil producer with an output of 18.60 million barrels per day (mbpd) – 20 per cent of the world’s total output. With an annual consumption of 20.51 mbpd, the US needs to import only a small quantity of oil.


Meanwhile, the UK too is eager to deepen its involvement in the Asia-Pacific. With Brexit, London has detached itself from the European strategic architecture and re-plugged into the Anglosphere. True, the UK has not been a heavyweight player in the Indo-Pacific for decades. However, US concern over China's growing clout and aggression in those waters causes it to welcome the support of its closest strategic partner.


Canberra too is plugging back into the Anglosphere. Australia’s armed forces have always demonstrated commitment towards their treaty obligations with the US, even sending troops into combat in Afghanistan and Iraq to pay what is pithily termed “the blood sacrifice”. Australia’s attitude towards China has been increasingly more belligerent, which is dangerous for Canberra, given its proximity to China, and its trade dependence on that country.


Alongside the outrage in Paris, there was consternation in New Delhi too over Washington’s readiness to give an AUKUS alliance partner nuclear technology for submarines, while denying India – a designated “major defence partner” and a key ally in the Indian Ocean – similar access to nuclear reactor technology for its planned line of SSNs and an aircraft carrier.


India’s submarine dilemma


Amidst this churning, New Delhi announced in June that it was tendering for the indigenous construction of six conventional submarines, powered by Air Independent Propulsion (AIP). Within India’s strategic community, a debate rages over the question – echoing that currently being heard in Australia – of whether the Indian Navy should be going in for conventional diesel-electric submarines, or AIP vessels or SSNs. 


In diesel-electric boats (as submariners incongruously refer to their submarines), large banks of batteries power electric motors that turn the submarine’s propellers. But the batteries quickly get discharged and the boat must surface every day or two to run onboard diesel generators, which require atmospheric air, to recharge their batteries. During battery charging, the surfaced submarine is vulnerable to detection since enemy radars quickly detect submarine masts or snorkels protruding above the surface.


To avoid detection, the ideal solution is nuclear propulsion. 


Nuclear reactors require no oxygen, which allows these submarines almost indefinite underwater endurance, limited only by human endurance and the amount of food that a submarine can carry. However, nuclear propulsion has serious technology challenges and India is still struggling to build a reactor small enough for an attack submarine.


AIP provides the next best solution, allowing submarines to remain underwater for up to two weeks, which provides the enemy with less opportunity to detect a surfaced boat.


The most common AIP systems use “fuel cell technology”, which generates power through the reverse electrolysis of oxygen and hydrogen, with the two elements chemically combining to generate electricity to charge the submarine’s batteries. Another technology solution for an AIP system is the Phosphoric Acid Fuel Cell (PAFC) technology. This solution, which the DRDO is developing, is more rugged, tolerant of fuel impurities, and offers longer life and efficiency.


However, hydrography (underwater geography) prevents the Indian Navy for opting for an all-conventional, or all-nuclear submarine fleet. That is because the underwater gradient in the Arabian Sea is so restricted that large nuclear submarines cannot come in close to the shore without scraping against the seabed. 50 kilometres out of Karachi, the seabed is just 50 metres deep, which is too shallow for nuclear submarine operations. Hence, in the Arabian Sea, conventional submarines – which are significantly smaller than nuclear boats – are essential for submerged operations.


India’s eastern coast, on the Bay of Bengal, however has a sharp gradient that allows even large nuclear SSNs to operate freely just a couple of kilometres out of harbour. Furthermore, conventional submarines cannot carry out the long transit submerged to patrol areas, such as the Malacca and Sunda Straits. They would need to recharge batteries en route, compromising operational secrecy. Therefore, India’s eastern coast needs large, nuclear SSNs that have long underwater endurance.


The Indian submarine project, therefore continues on two tracks: small conventional submarines for the Arabian Sea and an SSN programme for the Bay of Bengal. India has made a breakthrough in nuclear-propelled, nuclear armed submarines (SSBN) and the first of them, INS Arihant, is already operationally deployed in deterrence patrols. More SSBNs are in the pipeline.


However the SSN programme is proceeding only slowly. An American offer of nuclear propulsion technology, such as the one made to Australia, would be welcomed in New Delhi. However that would carry the quid pro quo of alliance burdens, a price that India, unlike Australia, is unwilling to pay.


Arming across the Asia-Pacific



New Weaponry






8 nuclear powered submarines

From UK under AUKUS


Tomahawk cruise missiles on warships



Long-Range Anti-Ship Missiles (LRASM) for F/A-18 and F-35A Lightning II fighters

Can hit targets at a range of 900 km


Precision guided missiles that can destroy targets from over 400 km planned for its land forces.



Australia and US to collaborate to develop hypersonic missiles.

Under the trilateral AUKUS security deal.


US has approved $3.5 billion sale of 29 Boeing AH-64E Apache attack helicopters to Australia






 Announced expenditure of $8.69 billion over the next five years to upgrade its weapons capabilities

This comes on top of planned military spending of $17 billion for 2022.


The programme will include a new, 1,200 km range, upgraded Hsiung Sheng cruise missile.



Taiwan has new "aircraft carrier killers" like the PLA’s Dong Feng 21D and Dong Feng 26.

Also developing its own submarines


Washington has approved sales of 100 Harpoon Coastal Defence Systems, three missile systems, artillery, and four aerial drones.

Worth about $5 billion in total


In August, Washington approved the sale to Taiwan of 40 x 155mm M109A6 self-propelled howitzers. 

The deal is valued at up to $750 million




South Korea

Tested a submarine-launched ballistic missile (SLBM) this month First non-nuclear country to develop such a system.

This is a variant of ground-based Hyunmoo-2B ballistic missile, with a range of about 500 km.


In 2020, South Korea proposed to build three submarines. Two of them, which displace 3,000 tons and 3,600 tonnes - will have diesel engines. However it is unclear how the third one, at 4,000 tonnes, would be powered.

Building a nuclear submarine has been among President Moon Jae-in election pledges, but he has never officially announced it after taking office in 2017.


Seoul has unveiled new missiles, including a supersonic cruise missile to be deployed soon



South Korea has been striving to develop solid-fuel rocket engines. This is intended to launch a spy satellite by the late 2020s.

Has successfully carried out a test firing in July.





It is mass producing the DF-26, a multipurpose weapon that can be fitted with nuclear warheads and has a range of up to 4,000 km.

It also has the DF-41 intercontinental ballistic missiles, the backbone of China’s nuclear deterrent.


The hypersonic DF-17 missile is said to manoeuvre at many times the speed of sound, making it more difficult to counter.



In 2019, China unveiled new unmanned aerial vehicles (UAVs)






It has spent millions of dollars on long-range air-launched weapons, and is developing a new truck-mounted anti-ship missile, the Type 12, with a 1,000 km range.



In 2020, Washington cleared the sale to Japan of 105 Lockheed F-35 fighters for about $23 billion













  1. Looks like INDIA might opt for the AIP submarines in future ….SSN are really required now by the country to ensure enemies don’t surface suddenly at 12 nautical miles of territorial waters !!

  2. Nicely illustrated article in simple terms for a common man like me. Thank you.

  3. How restricted are conventional submarines in operating in the North Arabian Sea? If it is difficult for submarines to approach the northern west coast of the Indian Arabian Sea, is it as difficult for Pakistan to launch submarines from it's naval facilities on it's coast? It will be very easy for India to patrol the Northern Arabian Sea for submarines. Why do we need to operate submarines in this region? Would it be more feasible to operate SSN'S in the maritime region where the Arabian Sea meets the Indian Ocean, and further beyond?
    If the adversary knows about SSN's patrolling this region beforehand, how effective would their surveillance be? Could we hinder their surveillance efforts?

  4. Odd tone you've adopted, Colonel. Insult to injury that a diesel electric submarine can't match the range and endurance of a nuclear sub? That's just a fact. It reflects, as you yourself note, a reassessment of Australia's threat environment. It has nothing to do with whether the French design is good or not.

  5. This comment has been removed by a blog administrator.


Recent Posts

Page 1 of 10412345...104Next >>Last