(DEFENCE SECURITY ASIA) — India is approaching a decisive moment in Project-75I, a proposed $8–10 billion programme for six advanced conventional submarines intended to reverse an emerging undersea capability gap across the Indian Ocean Region.

The programme would combine German submarine technology from Thyssenkrupp Marine Systems with construction by Mazagon Dock Shipbuilders Limited, placing operational urgency, technology transfer and indigenous production within a single strategically consequential procurement framework.

Project-75I has acquired renewed urgency because India’s ageing conventional submarine force faces simultaneous pressure from China’s expanding underwater fleet and Pakistan’s accelerating induction of Chinese-designed Hangor-class air-independent-propulsion submarines.

The proposed submarines, derived from the Type 214 and Type 214NG design lineage with Indian-specific adaptations, would introduce proven fuel-cell air-independent propulsion, extended submerged endurance and improved survivability against increasingly sophisticated anti-submarine warfare networks.

India’s existing Kalvari-class submarines entered service without operational air-independent propulsion, while older Sindhughosh-class and Shishumar-class boats are approaching retirement, creating a potentially dangerous force-structure contraction during the late 2020s and 2030s.

Pakistan’s commissioning of PNS Hangor on April 30, 2026, transformed a long-term planning concern into an immediate operational challenge because Islamabad now possesses a clear pathway towards fielding eight modern AIP-equipped attack submarines.

China compounds that pressure through a submarine fleet estimated at approximately 60–65 boats, sustained production capacity, expanding nuclear capabilities and growing underwater activity near strategic Indian Ocean sea lanes and maritime infrastructure.

The central question surrounding Project-75I is therefore no longer whether India requires new conventional submarines, but whether government approvals, industrial preparations and construction timelines can advance before regional capability disparities become operationally entrenched.

The programme has completed most major technical, commercial and financial stages, although a government-appointed group must still assess the depth and long-term value of TKMS’s proposed technology-transfer package before final strategic approval.

Once that assessment is completed, the proposal is expected to proceed to the Cabinet Committee on Security, whose clearance would authorise India’s highest-level strategic and financial commitment to the German-assisted submarine programme.

The first submarine is expected approximately seven years after contract signature, followed by one boat annually, meaning decisions taken during 2026 will shape India’s conventional underwater force posture well into the mid-2030s.

Project-75I consequently represents more than another defence acquisition, because its outcome will influence Indian sea-denial capacity, India-Germany defence-industrial relations, regional deterrence calculations and New Delhi’s ambition to establish sovereign submarine-design capabilities.

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Pakistan’s Hangor Submarines Accelerate India’s Strategic Countdown

Pakistan signed its agreement with China in 2015 for eight Hangor-class submarines, creating a structured acquisition programme combining Chinese construction, Pakistani assembly, technology transfer and the progressive modernisation of Islamabad’s conventional underwater force.

Four submarines are being constructed at China’s Wuchang Shipbuilding facilities, while another four are planned through Karachi Shipyard and Engineering Works, giving Pakistan both operational platforms and experience in complex submarine production.

The lead submarine, PNS Hangor, was commissioned at Sanya, China, on April 30, 2026, before arriving in Karachi during June, demonstrating that Pakistan’s programme had moved from procurement planning into operational force generation.

Three additional Chinese-built submarines—Shushuk, Mangro and Ghazi—were launched during 2025 and are expected to enter service between late 2026 and mid-2027, although Pakistani-built vessels could face longer schedules extending into the early 2030s.

Displacing approximately 2,800 tonnes, the Hangor class incorporates Stirling-cycle air-independent propulsion and can carry torpedoes, anti-ship missiles and potentially the nuclear-capable Babur-3 submarine-launched cruise missile, substantially widening Pakistan’s possible underwater mission set.

Air-independent propulsion allows these submarines to remain submerged for days or weeks without frequently snorkelling, reducing exposure to maritime patrol aircraft, unmanned systems, satellites, surface combatants and other anti-submarine warfare sensors.

Once the full Hangor class becomes operational, Pakistan could possess approximately eight to eleven AIP-equipped submarines when upgraded Agosta 90B boats are included, creating a temporary numerical and endurance advantage over India’s conventional fleet.

That prospective advantage would complicate Indian sea-denial operations, carrier and surface-group protection, anti-submarine warfare deployments and surveillance across the Arabian Sea, particularly if Pakistani submarines can sustain longer patrols near strategic approaches.

The possibility of Hangor-class deployments beyond Pakistan’s immediate maritime approaches, including towards the Bay of Bengal, introduces a broader planning problem by potentially connecting Pakistani submarine operations with China’s expanding Indian Ocean presence.

Although Pakistan’s programme is not the sole justification for Project-75I, its visible progress has sharpened the consequences of delay and reinforced India’s requirement to restore AIP parity before older submarines leave operational service.

China’s Expanding Fleet Reshapes the Indian Ocean Battlespace

China maintains one of the world’s largest submarine forces, estimated at approximately 60–65 vessels during 2026, including modern diesel-electric submarines, AIP-equipped platforms and an expanding nuclear-powered attack and ballistic-missile submarine component.

Current projections indicating approximately 70 Chinese submarines by 2027 and around 80 by 2035 suggest that Beijing’s undersea advantage will increasingly reflect not only fleet size, but also production continuity and technological renewal.

Chinese research vessels and other dual-use maritime activities across the Indian Ocean add another layer of uncertainty because hydrographic, oceanographic and acoustic information can support submarine navigation, sensor employment and future operational planning.

Beijing’s defence-industrial relationship with Islamabad magnifies India’s challenge by enabling Pakistan to acquire modern submarine technology while creating infrastructure, training pipelines and maintenance capacity capable of sustaining a larger underwater force.

For Indian planners, this creates a potential two-front undersea problem spanning the Arabian Sea, Bay of Bengal and wider Indian Ocean, requiring submarines capable of persistent surveillance, discreet interception and operations beneath hostile sensor coverage.

Conventional submarines remain particularly valuable within shallow, acoustically complex waters because smaller diesel-electric boats can conduct sea denial, intelligence collection, mine-laying and anti-surface warfare while presenting difficult detection problems for opposing forces.

A shrinking Indian conventional fleet would reduce patrol availability because maintenance cycles, crew training and refits prevent every submarine from deploying simultaneously, making nominal fleet totals substantially different from usable operational strength.

The strategic danger therefore lies not simply in China possessing more submarines, but in Beijing sustaining deployments, supporting Pakistan’s modernisation and forcing India to divide finite anti-submarine warfare resources across multiple maritime theatres.

Project-75I would not erase China’s numerical superiority, although six advanced submarines could strengthen India’s ability to monitor maritime chokepoints, protect critical sea lines of communication and impose uncertainty upon hostile naval planning.

Its deterrent value would derive from survivable deployment and credible weapons employment rather than numerical symmetry, making acoustic discretion, submerged endurance, sensor integration and reliable logistics more strategically important than headline fleet comparisons.

Fuel-Cell AIP Could Transform India’s Underwater Endurance

The defining capability within Project-75I is its proposed air-independent-propulsion system, expected to use scaled-up Siemens polymer-electrolyte-membrane fuel-cell technology adapted by TKMS for submarines displacing approximately 2,500–3,000 tonnes or more.

Traditional diesel-electric submarines must periodically approach snorkelling depth to run diesel engines and recharge batteries, creating detectable acoustic, infrared, radar and visual signatures that expose them to increasingly networked anti-submarine warfare forces.

AIP enables electricity generation while the submarine remains submerged, potentially extending underwater endurance to approximately two or three weeks and allowing commanders to minimise exposure during surveillance, ambush, evasion and intelligence-gathering operations.

Longer submerged endurance becomes particularly consequential near adversary-controlled waters, where maritime patrol aircraft, helicopters, surface combatants, unmanned vehicles and space-based surveillance can rapidly exploit even brief snorkelling or communications signatures.

Fuel-cell propulsion also produces low acoustic signatures because it avoids the machinery cycles associated with conventional diesel operation, strengthening the submarine’s ability to remain concealed while monitoring shipping routes or preparing weapon engagements.

India’s six Kalvari-class Scorpène submarines were delivered without operational AIP, although a domestically developed system is planned for later retrofit, leaving the current force dependent upon traditional battery and diesel-generation cycles.

Project-75I would introduce AIP from the beginning of service, avoiding some integration complexities associated with retrofitting and giving the Indian Navy a larger platform designed around extended underwater endurance, power generation and mission systems.

This capability would support sea denial, anti-submarine warfare, intelligence, surveillance and reconnaissance, mine-laying and protection of critical sea lines connecting India with energy suppliers, trading partners and distant operational areas.

AIP nevertheless does not make conventional submarines equivalent to nuclear-powered boats, because speed, endurance and sustained high-power operations remain constrained, although quietness can create substantial tactical advantages within contested littoral environments.

The programme’s operational significance therefore rests on combining AIP with trained crews, dependable weapons, sensor fusion, maintenance capacity and secure communications, since propulsion technology alone cannot compensate for weaknesses across the wider combat system.

German Technology Transfer Tests India’s Self-Reliance Strategy

Project-75I is structured under India’s strategic partnership model, requiring Mazagon Dock Shipbuilders Limited to construct the submarines domestically while TKMS transfers selected design knowledge, manufacturing processes, training support and AIP-related expertise.

The programme requires indigenous content to begin at approximately 45 percent for the first submarine and rise towards 60 percent by the sixth, progressively expanding Indian industrial participation throughout the production sequence.

This graduated localisation model is intended to move India beyond assembling imported components by developing specialised suppliers, engineering knowledge, quality-control systems and maintenance expertise required to support submarines throughout decades of operational service.

A government-appointed technical evaluation group is examining whether the proposed transfer package provides meaningful access to design, manufacturing and propulsion expertise, rather than limiting Indian participation to production activities without sovereign technical understanding.

That review represents the final major pre-approval hurdle because inadequate technology transfer could leave India dependent upon overseas suppliers for upgrades, maintenance, certification and critical components despite constructing the hulls domestically.

The programme’s industrial value also depends upon production continuity, since experienced designers, welders, systems integrators and specialised suppliers can disperse when long intervals separate submarine projects, weakening the national manufacturing ecosystem.

Knowledge acquired through Project-75I is expected to support Project-76, India’s planned indigenous conventional submarine initiative, which aims for higher domestic content and prospective induction beginning during the mid-2030s.

An option for three additional P-75I submarines could preserve production capacity, distribute fixed industrial costs and increase fleet mass, although any expansion would depend upon future funding, operational requirements and construction performance.

The programme simultaneously deepens India-Germany defence-industrial cooperation, supported by an intergovernmental agreement covering long-term assistance, technology transfer, personnel training, administrative clearances and export approvals needed for sustained implementation.

Success would diversify India’s submarine partnerships while reducing long-term dependence upon traditional suppliers, but meaningful strategic autonomy will ultimately require domestic mastery of design authority, propulsion integration, weapons certification and lifecycle support.

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Final Approval Will Determine India’s Undersea Force Posture

The MDL–TKMS proposal became the sole technically compliant offer after evaluation, while the competing Larsen and Toubro–Navantia bid failed to satisfy technical requirements, principally those concerning a proven operational air-independent-propulsion system.

Commercial bids were opened in early 2025, followed by extensive negotiations that reportedly rationalised the projected programme cost to approximately $8–10 billion, although the final contractual value remains subject to government approval.

India’s Finance Ministry cleared the proposal during late May 2026, removing a major financial obstacle and allowing the remaining discussion to concentrate upon technology-transfer depth, strategic value and final Cabinet-level authorisation.

An intergovernmental agreement signed during German Chancellor Friedrich Merz’s January 2026 visit established the political and administrative framework for long-term support, training, export approvals and cooperation between the participating governments and industries.

Indian Defence Minister Rajnath Singh subsequently visited Germany and toured TKMS facilities in Kiel during April 2026, reinforcing high-level political momentum behind a programme carrying significant operational and industrial consequences for both countries.

German Defence Minister Boris Pistorius indicated that contract signature was expected within months, while German Ambassador Philipp Ackermann publicly expressed optimism about early finalisation, although such statements do not constitute Indian governmental approval.

TKMS also described negotiations as being in their final phase and began expanding relationships with Indian companies, including cooperation involving heavyweight torpedoes and anti-submarine warfare systems, indicating preparations for a broader industrial footprint.

After the technology-transfer assessment, the proposal must receive Cabinet Committee on Security approval before MDL and TKMS can sign the contract, finalise detailed designs, allocate workshare and begin funded construction activities in Mumbai.

The delivery schedule remains strategically unforgiving because a submarine contracted during 2026 would not arrive until approximately the early-to-mid 2030s, followed by subsequent boats at roughly annual intervals under the stated programme framework.

Further delay would therefore widen the interval between Pakistan’s Hangor induction and India’s P-75I deployment, while accelerating retirements among older Indian submarines could reduce operational availability during an increasingly contested regional security transition.

Project-75I cannot independently resolve every Indian undersea vulnerability, but final approval would establish a credible path towards restoring conventional submarine mass, increasing submerged endurance and preserving an indigenous production base for future programmes.

The programme’s ultimate strategic measure will be whether India converts German technological assistance into deployable submarines, resilient logistics and sovereign design competence before regional undersea competition hardens into a lasting operational disadvantage.