India’s plan to build nuclear-powered attack submarines could be bad news for China. A fleet of nuclear attack subs – among the most lethal weapons on Earth – prowling the Indian Ocean could threaten Beijing’s growing naval presence in the region.

Or, a fleet of nuclear subs could be a boondoggle that drains India’s limited military resources. Even some Indian experts believe the Indian Navy would be better off buying cheaper diesel-electric subs more suitable for missions such as coastal defence.

All of which raises a question for emerging powers such as India, which has the seventh-largest economy on the planet. Are the prestige and capabilities of nuclear subs worth the cost?

For now, the nationalist government of Prime Minister Narendra Modi favours the nuclear option. Within the next two months, the government is likely to approve a plan to build three nuclear-powered attack subs, followed by another three later on, according to the Times of India.

“The overall project is for the construction of six nuclear-powered attack submarines (called SSNs in naval parlance), each weighing over 6,000 tons, at the ship-building centre (SBC) at Vizag,” the Times reported. “But only three will be approved by the CCS [Cabinet Committee on Security] in the first go, with the first indigenous SSN slated to roll out by around 2032 or so. Though each will cost around Rs 15,000 crore [US$2.3 billion], the funding will not be a major problem because it will be spread over several years, said the sources.”

This marks a radical departure from India’s 1999 sub-building plan, which called for construction of 24 diesel subs over 30 years. The Indian Navy currently operates 11 older diesel subs – Russian Kilo-class and German Type 209 boats – plus three newer French Scorpene-class 1,870-ton attack boats. However, the Modi government appears to be revising the 1999 plan to include a mix of six nuclear attack subs and 18 diesel-electric boats. The Indian Navy currently operates a single SSN, the INS Chakra – which is actually a Russian Akula-class attack sub on a 10-year lease. India previously leased a Soviet Charlie-class nuclear sub in the late 1980s, and in 2019, India signed a 21,000 crore (US$3 billion) deal to lease a more advanced Akula-class boat.

In addition to attack subs, India already has one nuclear-powered ballistic submarine (SSBN), the INS Arihant, in service, with a second SSBN – the Arighat – scheduled to be commissioned in 2021. Armed with K-15 missiles with a 500-mile range, these boats are part of India’s strategic triad of land-based ballistic missiles and nuclear-armed fighter bombers, aimed at India’s nuclear-armed rivals Pakistan and China. There are also plans to build two 7,000-ton SSBNs.

In addition, “an even bigger 13,500-ton SSBN is also being planned, while the new K-4 missiles, with a strike range of 3,500 kilometres [2,174 miles], are now virtually ready,” the Times said. Though smaller than the 18,750-ton U.S. Ohio-class ballistic missile subs, the new vessel would dwarf India’s current submarines.

The new sub plan comes as China expands its presence in the Indian Ocean, including survey ships mapping the region, a naval base at Djibouti, and Beijing’s push for another base in the Maldives. This has left Indian defence planners – already confronting Chinese troops on India’s northern border – with a Chinese threat in India’s maritime backyard.

Nuclear Versus Diesel Subs

The Times of India believes that nuclear attack subs offer economic as well as military benefits. “India, of course, needs to build its own SSNs because they will not only prove cheaper but also give a major boost to the local economy,” the newspaper said. “Nuclear submarines can operate at high speeds for long distances as well as remain submerged for months at end, without having to surface or ‘snorkel’ every few days to get oxygen to recharge their batteries like conventional diesel-electric submarines.

However, diesel-electric subs might be the better choice for India, argues Abhijit Singh, a former Indian naval officer and now an analyst at India’s Observer Research Foundation thinktank. “Despite the distinct advantages that SSNs enjoy over conventional subs, the latter offers benefits in littoral waters that more than adequately offset their most glaring constraint –limited operating endurance,” Singh told Forbes.

“The SSK [diesel-electric sub] has a smaller hull that is easier to manoeuvre in shallow waters and harder to detect. The fact that it costs a fraction of the price of a typical nuclear sub, makes the diesel electric an irresistible proposition for the Indian navy. Its attractiveness is only enhanced by the ease of operation and the absence of the risk of dangerous nuclear leaks.”

Nuclear and diesel-electric subs are like cats and dogs: both attract admirers and detractors who can offer any number of reasons to support their views. SSN proponents point to the ability of nuclear-powered submarines to remain submerged almost indefinitely, which means they neither have to return to port to refuel, or surface to recharge their batteries. Nuclear power gives subs virtually unlimited range as well as underwater speeds of up to 30 knots, which makes them faster than diesel subs as well as many surface ships.

Nuclear subs are bigger than their diesel counterparts, and with plentiful electricity from the reactors, they can carry advanced sensors and plenty of torpedoes, anti-ship missiles and land-attack cruise missiles. But all these features come at a hefty price: a U.S. Virginia-class nuclear attack sub costs around $3.5 billion, plus the financial and environmental costs of maintaining and eventually decommissioning a radioactive ship.

Diesel-electric subs lack the speed and endurance of their nuclear-powered counterparts. On the other hand, diesel boats have come a long way since World War II, when they could only sail underwater for a few hours before needing to surface to recharge their batteries. Vessels equipped with Air-Independent Propulsion systems can travel submerged for weeks at a time. Compared to relatively noisy nuclear reactors and their cooling systems, AIP subs are so quiet that many navies worry that their anti-submarine warfare systems won’t be able to detect them. Perhaps most important, an advanced diesel-electric sub like France’s Scorpene-class vessels cost around $500 million apiece.

Different Subs For Different Navies

For the U.S. Navy, with its submarines deployed all around the globe, the unlimited endurance of nuclear subs is worth the money (though some believe diesel subs have a place in the U.S. Navy). For Russia and China, which conduct some blue-water operations but still tend toward coastal defence and regional operations in near waters, a mix of nuclear and diesel subs works well.

But what of India? Nuclear power for ballistic missile subs is logical, because these are vessels that do not want to be caught in port by a first strike. And there is no doubt that nuclear-powered submarines are prestige items. Though not as visible a symbol as aircraft carriers, mastering the technological and shipbuilding skills to build nuclear warships is an achievement.

On the other hand, India’s defence budget was just $64 billion in 2020, compared to $193 billion for China and $738 billion for the U.S., estimates the International Institute for Strategic Studies. Beset by potential threats on multiple fronts, including border clashes with Chinese troops along the Himalayas, the growing Chinese naval presence in the Indian Ocean, and tensions with perennial arch-enemy Pakistan, Indian defence resources are already stretched thin. The money spent on nuclear attack subs may mean the sacrifice of a third Indian aircraft carrier. While some would argue that nuclear subs are more valuable – or less vulnerable – than aircraft carriers, both projects

In the end, it comes down to what India wants to do with its submarines. If it wants to project power and fear into distant waters – the South China Sea comes to mind – then nuclear attack subs are a perfect tool for applying military power and diplomatic coercion. But if the goal is merely to keep China out of the Indian Ocean, then diesel subs can perform the mission from Indian bases far more cheaply.

This is not just a question for India. South Korea also plans to build nuclear-powered attack submarines, Brazil is already building one, and it’s easy to imagine other nations – Australia, Israel, perhaps even Japan – joining the atomic sub club. Whether these nuclear attack subs will be awesome weapons – or just feel-good prestige projects – remains to be seen.