The recent commissioning of INS Aridhaman, the Indian Navy’s (Indian Navy) third indigenously designed Arihant-class nuclear-powered ballistic missile submarine (SSBN), highlights India’s capability to develop advanced strategic underwater platforms, while still struggling to produce significantly less complex conventional diesel-electric submarines (SSKs) without overseas collaboration.A cross-section of veteran and serving naval officers note that while India’s SSBN programme continues to advance – evident in the Arihant-class platform and the planned commissioning of a fourth, more advanced platform, codenamed S4*, likely to enter service around 2027-28 – this momentum sharply contrasts with the chronic stagnation of conventional SSK projects.This steady progression in sea-based nuclear capability is central to completing and sustaining India’s nuclear triad, ensuring a survivable second-strike capability across land-, sea- and air-based delivery systems.Against this backdrop, these officers argue that this divergence exposes a deeper systemic dysfunction, wherein the defence industrial ecosystem is capable of delivering high-end, strategically prioritised platforms, but struggles to produce routine, yet operationally essential, conventional SSKs.In their assessment, “extraordinary” programmes like SSBNs, ballistic and cruise missile projects and other strategic systems have succeeded precisely because they were insulated, prioritised and backed by sustained political support – shielded from the Ministry of Defence’s cumbersome procurement procedures, shifting service requirements and the constant risk of bureaucratic or political disruption.By contrast, SSK programmes have remained mired in procedural inertia, compounded by evolving operational demands and inconsistent long-term planning, leaving them vulnerable not only to capability gaps but also to protracted delays and even cancellation.Former Indian Navy Chief of Staff Admiral Arun Prakash offers a blunt explanation for this dysfunctionality. “India’s conservative defence establishment remains fundamentally risk-averse and unable to accept failure as part of the developmental process, regardless of the eventual outcomes”, he says.In such an environment, he declares, procedural correctness is prioritised over results and any misstep – technical, financial or managerial – can trigger audits or investigations, creating a culture in which officials are disincentivised from taking bold decisions. Consequently, concerned officials, he added, tended to defer responsibility, routinely opting for proven foreign platforms over riskier, but desired indigenous SSK development.‘Formula 1 to high-end SUV’One Indian Navy submariner captured this divergence more dramatically, likening SSBN construction to locally engineering a Formula 1 race car and SSK production to building an advanced sports utility vehicle (SUV). “It is a staggering gap,” he says, requesting anonymity. “A system that can deliver a Formula 1 machine somehow stalls when asked to produce a high-end SUV – revealing an ecosystem capable of extraordinary feats under priority, but struggling with routine output amid procedural drag”, he adds.This contrast reflects a broader structural reality: shielded by strategic prioritisation and sustained political backing, flagship programmes like the Arihant-class SSBNs have progressed steadily, with a fourth boat – codenamed S4* and likely to be commissioned as INS Arisudan around 2027-28 – already in the pipeline. Conventional SSK efforts, however, continue to be constrained by bureaucratic inertia, shifting requirements and ad hoc planning – an enduring pattern exemplified by the Indian Navy’s nearly two-decade-old Project-75 India.Shielded by strategic prioritisation and high-level political backing, this model is evident in the steady progression of the three Arihant-class boats, to be followed by a fourth SSBN – codenamed S4* and likely commissioned as INS Arisudan around 2027-28. In contrast, conventional SSK programmes remain mired in bureaucratic drag, shifting requirements and an ad hoc approach, amply illustrated by the Indian Navy’s nearly two-decade-old Project-75 India.Initiated in 2007 to locally build six SSKs equipped with air-independent propulsion (AIP) and land-attack capability, Project-75 India remains stalled nearly two decades later, still awaiting finalisation of the protracted agreement between Mazagon Dock Shipbuilders Limited (MDL) and Germany’s ThyssenKrupp Marine Systems (TKMS). This delay is driven less by technical complexity than by organisational shortcomings rooted in fragmented decision-making, a rigid, rule-bound procurement culture, with little or no accountability.Hobbled by the defence ministry’s stringent procurement requirements and evolving naval qualitative requirements (QRs), the Project-75 India illustrates that the divergence in progress between India’s SSBN and SSK programmes is organisational, not technically driven.Funding, clear timelines and insulationIn sharp distinction, the SSBN programme – centred on the hush-hush Advanced Technology Vessel project formally launched around 1984 and executed at the secretive Ship Building Centre in Visakhapatnam – was never a standard industrial exercise. Instead, it was a tightly controlled, state-driven and highly classified national mission managed and monitored by the Prime Minister’s Office and implemented by a small, empowered cadre from the Defence Research and Development Organisation (DRDO), the Department of Atomic Energy and a select core of naval personnel.The SSBN project also benefited from assured funding, extended timelines and insulation from intrusive scrutiny and audit pressures that typically plague other military programmes, particularly those involving SSKs. Furthermore, it was cushioned by inbuilt shock absorbers that allowed it to navigate repeated failures and endure over decades, without the constant risk of cancellation or scandal.Conversely, the absence of comparable institutional protection for SSK programmes was starkly evident during what several generations of Indian Navy officers ruefully term the ‘lost decade’ between 1995 and 2005, when MDL’s newly established submarine construction facilities lay idle in the aftermath of the unresolved HDW corruption scandal linked to the late-1980s import of four German Type 209/1500 boats.Investigations uncovered procedural irregularities but stopped short of securing meaningful convictions, even as the fallout paralysed India’s SSK-building ecosystem. Many retired submariners directly attribute the current SSK shortfall to this prolonged period of inaction, which disrupted programme continuity, left MDL without orders and discouraged private sector participation.The resulting reliance on ageing Russian- and German-origin SSKs overstretched maintenance cycles and by the time Project 75 – for the licensed construction of six French Scorpene-class submarines at MDL – began in late 2006, the Navy had already fallen significantly behind in conventional underwater capability. Analysts view this extended phase of bureaucratic inertia as a structural failure, in sharp contrast to the steady advancement of the SSBN programme.A senior industry official in New Delhi framed the issue in operational terms, noting that the SSBN programme illustrated how tightly ‘ring-fenced’, high-priority projects can bypass systemic drag. “Everything outside that strategic bubble – no matter how operationally critical – gets trapped in layers of process, moving at a crawl,” he says, declining to be named. The result, he cautioned, is a system capable of delivering efficiency in isolation, but not consistency at scale.The propulsion systemPropulsion remains one of the most formidable challenges in India’s SSK programme, underscoring a broader weakness in the country’s defence industrial capability to indigenously develop advanced powerplants – a handicap duplicated across diverse platforms from combat and rotary aircraft to armoured systems.At its core, an SSK’s effectiveness hinges on endurance and stealth – how long it can remain submerged and how quietly it can operate undetected – both governed by an integrated propulsion ecosystem comprising diesel engines for charging, batteries for underwater movement and air-independent propulsion (AIP) systems that extend submerged endurance.More critically, India’s most serious deficiency lies not in individual components, but in integrating this entire propulsion chain – along with associated acoustic controls – reflecting limited industrial depth in submarine design and construction. Acoustic discretion is equally critical, as propulsion systems are the primary source of a submarine’s noise signature. Besides, designing ultra-quiet engines, alongside vibration-dampening mounts, advanced propellers and noise-suppressing materials, demands decades of refinement – an area where India still lacks proven capability.Recent efforts to bridge these gaps remain incremental. The DRDO’s AIP system, developed by the Naval Materials Research Laboratory (NMRL), has progressed from land-based trials towards operational deployment, with plans to retrofit the Kalvari-class SSKs beginning next year. Its fuel-cell technology is reportedly capable of extending the SSK’s submerged endurance to around two weeks, but its real test will lie in demonstrating sustained, quiet and reliable performance at sea compared to proven German AIP systems.Battery technology also presents a parallel constraint. While global submarine fleets are transitioning to lithium-ion systems that significantly enhance endurance, India has yet to field a domestically developed, combat-ready equivalent – further underscoring the depth of its overall propulsion challenge.Meanwhile, set against these inherent challenges with regard to SSKs, it is equally imperative to scrutinise the self-laudatory narrative amplified by sections of the domestic media during the April 3 commissioning of INS Aridhaman at the SCB in Visakhapatnam. This implied that the Indian Navy’s third SSBN – like its predecessors – was an entirely indigenous achievement developed in isolation.Russia’s roleSuch coverage made scant mention of the crucial role played by Russian specialists in India’s SSBN programme, particularly in the highly complex task of miniaturising the submarines’ 82.5 MW pressurised light water reactor reactors – a contribution long acknowledged discreetly but frequently downplayed in public discourse. Indeed, the launch of INS Arihant, the lead SSBN, at the SCB in July 2009 marked the first visible acknowledgement of this collaboration, with a Russian naval design team and then-ambassador V.I. Trubnikov was present at the ceremony.The roots of this partnership stretch back to Project 932 in the late 1970s, initiated under the DEA and the Navy’s Directorate of Marine Engineering. Its strategic impulse lay in the aftermath of the 1971 war, when the United States deployed an aircraft carrier-led task force into the Bay of Bengal in support of Pakistan, in recognition of Islamabad’s role in providing Washington access to China.At India’s request, the Soviet Union – bound by a recently concluded bilateral Friendship Treaty between Delhi and Moscow – dispatched nuclear-powered attack submarines or SSNs from Vladivostok to counter this show of force. The operational authority and strategic impact of these Soviet SSNs left a lasting impression on PM Indira Gandhi’s government, catalysing the decision to pursue a similar capability.Progress thereafter was uneven. Early reactor development efforts faltered around 1980, nearly stalling the programme before it was reconstituted under the DRDO as the ATV project. A major inflection point came in 1988, when the Indian Navy leased INS Chakra, a 5,000-tonne ‘Charlie I’-class SSN from Moscow for three years, making India the sixth country after China, France, Russia, the UK and the US to operate such a platform.In 2012, a second SSN – an Akula-class, also named Chakra – was leased to further boost India’s SSBN expertise, but it was returned in June 2021 due to powerplant and maintenance issues. A third SSN lease, originally set to begin in 2025, has now been delayed to 2027–28, amid Russian supply-chain disruptions and sanctions related to the Ukraine war.Operations of both Chakra SSNs, closely supervised by Russian engineers, were highly classified, with only a few Indian officers and DAE scientists fully privy to the workings of spent nuclear fuel and reactor systems. Senior retired Indian Navy personnel, who served on the respective Chakra SSNs, note that lessons learned from these platforms were foundational to the SSBN programme, directly feeding into the development of the Arihant-class boats.In parallel, India’s SSBN programme will eventually be complemented by the indigenous construction – also at the SCB – of 3-5 SSNs, approved by the government in early 2015, with the first 6,000-tonne boat expected to be ready by 2032-33. This supplementary effort gained urgency as the Navy’s 1999 plan for 24 AIP-equipped SSKs slipped by almost 15 years, leaving the Indian Navy critically short of conventional boats. The resulting capability gap prompted a strategic rethink, leading to the inclusion of six SSNs within the 24-submarine force to provide greater reach and flexibility in an increasingly hostile environment in the strategic and Indian Ocean Region.In this context, Russia’s role emerges as foundational rather than peripheral – less a supplier than a long-term enabler of capability, bridging technological gaps that would otherwise have stalled the programme indefinitely. India’s SSBN fleet, therefore, is best understood not as a purely indigenous achievement, but as the most sophisticated outcome of a deeply embedded Indo-Russian strategic partnership – one that, by virtue of its structural and technological interdependence, is set to persist and evolve over the long term.