Russia has proposed supplying India with three refurbished Kilo-class diesel-electric submarines, valued at under $1 billion, as an immediate boost to the Indian Navy's underwater capabilities. Defences sources say that this offer emerged shortly after President Vladimir Putin's visit to New Delhi in early December 2025, where discussions included a future lease of an Akula-class nuclear-powered submarine by 2028.

The Kilo-class vessels, drawn from Russia's surplus reserves, serve as a cost-effective interim measure amid delays in India's Project 75I program.

Each submarine will undergo extensive modernisation to extend its service life by 20 years, with an estimated cost below $300 million per vessel. Key upgrades include integration of the Klub-S missile system, the export variant of the Kalibr, which launches from torpedo tubes to engage land and anti-ship targets at 220-300 km ranges.

Additional enhancements encompass low-observable stealth coatings for sonar evasion, automated periscope systems, and modern lithium-ion batteries to boost endurance.

This proposal marks a reduction from an earlier July 2025 offer of six submarines, tailored to align with India's current financial and operational priorities.

The deal directly addresses the retirement of three Kilo-class boats—INS Sindhurakshak in 2017, and INS Sindhuvir and INS Sindhudhwaj between 2017 and 2022—providing one-to-one replacements. 

Meanwhile, the Indian Navy marked a poignant milestone on 19 December 2025, as INS Sindhughosh, the lead submarine of her class, was decommissioned after four decades of exemplary service.

Such measures prevent further depletion of the fleet, which remains effective in strategic areas like the Malacca Strait despite age-related maintenance challenges.

India's conventional submarine fleet stands at 16 vessels as of late 2025: seven Russian Sindhughosh-class (Kilo), four German HDW Shishumar-class, and six French-designed Kalvari-class (Scorpene). Without swift acquisitions, projections indicate the fleet could shrink to single digits by the mid-2030s, undermining maritime security in the Indian Ocean region. The ageing Kilo platforms, acquired between 1986 and 2000, form the backbone but face operational availability constraints.

The Klub-S system, already familiar to the Indian Navy, enhances lethality with its 400-kg warhead, precise guidance, and ability to manoeuvre around obstacles even in adverse conditions.

A related deal in February 2025 secured Klub-S missiles specifically for submarine operations, underscoring deepening India-Russia defence ties. These upgrades position the refurbished submarines to meet modern warfare standards, bridging gaps until indigenous projects mature.

Nuclear-powered submarines offer superior submerged endurance, stealth, and range over diesel-electric types, enabling extended patrols critical for Indian Ocean security against threats from China and Pakistan. Restricted to training, it builds expertise for India's indigenous SSNs while deepening Russia ties amid global shifts.​ This fits India's indigenisation goals, with prior Chakra leases (ending 2021) providing operational lessons.

Russia's timely intervention reflects its role as a reliable partner in bolstering India's naval strength, particularly as geopolitical tensions in the Indo-Pacific intensify. The package not only sustains fleet numbers but also infuses advanced technology at a fraction of new-build costs.

Negotiations advance amid broader strategic cooperation, including nuclear submarine leases and missile integrations like BrahMos on Akula-class platforms. 

India's own ballistic-missile submarine program nears a pivotal milestone with the third SSBN, INS Aridhaman, in its final trials and poised for imminent commissioning, as confirmed by Navy Chief Admiral Dinesh K Tripathi.

Larger than the inaugural INS Arihant (operational since 2018) and INS Arighaat (since 2024), this vessel will accommodate an expanded arsenal of K-4 missiles boasting a 3,500 km range—doubling Arighaat's capacity—while the forthcoming 7,000-ton S-4 submarine is slated for 2027 induction.

These advancements, alongside developing K-5 and K-6 missiles extending reach to 5,000-6,000 km and future 13,500-ton SSBNs with enhanced reactors, bolster the survivability of India's no-first-use nuclear deterrent, cementing sea-based platforms as the triad's stealthiest pillar capable of prolonged submerged operations.
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This development signals Moscow's commitment to New Delhi's defence indigenisation goals while offering proven, battle-tested solutions. It also aligns with India's strategic push for enhanced naval presence in the Indian Ocean amid regional tensions. 

IDN (With Agency Inputs)

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