Project-75I: How India’s $8-billion submarine bet reshapes the Pakistan–China equation

More than five decades after Indian naval strikes crippled Karachi during the 1971 war, undersea power has again moved to the centre of New Delhi’s strategic calculations. Project-75I — the Indian Navy’s plan to induct six next-generation conventional submarines — has gathered momentum amid renewed friction with Pakistan, China’s expanding submarine footprint in the Indian Ocean, and Germany’s growing strategic engagement with India. Together, these strands explain why what appears to be a procurement decision is, in fact, a recalibration of India’s maritime deterrence.

What exactly is Project-75I?

Project-75I is the Indian Navy’s flagship programme to acquire six advanced diesel-electric submarines equipped with fuel-cell-based air-independent propulsion (AIP), modern sensors, torpedoes and missile systems. Cleared under the Strategic Partnership Model, the project emphasises indigenous construction, long-term transfer of technology, and the creation of a domestic submarine-building ecosystem.

Initially estimated at over ₹40,000 crore, the programme’s overall value is now assessed at around $8 billion (roughly ₹72,000 crore), factoring in configuration choices and lifecycle support. For the Navy, the project is intended to arrest a steady decline in conventional submarine numbers even as undersea activity around India intensifies.

Why the submarine shortfall worries the Navy

India’s conventional submarine arm is ageing. While newer boats have entered service, several older platforms are approaching the end of their operational life. At the same time, both Pakistan and China are investing heavily in undersea warfare.

For planners in the Indian Navy, submarines remain the most survivable and versatile tools for surveillance, sea denial and deterrence. Unlike surface combatants, they can loiter silently, monitor choke points and threaten high-value targets without escalating visibly — a capability increasingly relevant in crisis scenarios.

Why Germany’s Type-214NG emerged on top

After a prolonged evaluation, the Navy selected the German Type-214 Next Generation design, edging out Spain’s competing offer. The decisive factor was the maturity of Germany’s fuel-cell-based AIP system, widely regarded as operationally proven.

AIP allows a submarine to remain submerged for weeks without surfacing or snorkelling, sharply reducing detection risk. In crowded and contested waters, endurance and acoustic stealth matter more than experimental features. The German design’s lower lifecycle risk appears to have weighed heavily in the Navy’s calculus.

Make in India, not just import substitution

All six submarines are to be built at Mazagon Dock Shipbuilders Limited, with Germany’s ThyssenKrupp Marine Systems acting as design authority and technical partner. Indigenous content is expected to rise from about 45% in the first boat to nearly 60% by the sixth.

For the government, Project-75I is less about buying platforms and more about absorbing complex design, integration and construction skills. The logic is to ensure that future submarine programmes rely far less on foreign blueprints.

Pakistan, Karachi and the logic of sea denial

India’s focus on undersea power is rooted in history. During the 1971 war, Indian naval operations against Karachi disrupted Pakistan’s fuel supplies and maritime trade, hastening the conflict’s end. That lesson has resurfaced in recent crises.

Karachi remains Pakistan’s principal economic and energy lifeline. Even without firing a shot, India’s ability to credibly threaten maritime access through submarines imposes strategic caution on Pakistan. Submarines with extended underwater endurance would only sharpen that deterrent effect.

China’s expanding shadow beneath the waves

Beyond Pakistan, China looms large in India’s threat perception. The People’s Liberation Army Navy operates a rapidly expanding submarine fleet, including nuclear-powered platforms that have begun appearing more frequently in the Indian Ocean.

Chinese submarine deployments, port calls and patrols — combined with Beijing’s support to Pakistan’s undersea modernisation — have heightened Indian concerns. For New Delhi, countering this challenge requires a credible conventional submarine force capable of tracking adversary boats and denying access to critical sea lanes.

Why timing matters in India–Germany ties

The renewed push behind Project-75I coincides with Germany’s effort to deepen its strategic presence in the Indo-Pacific. Defence industrial cooperation has emerged as a key pillar of the broader India–Germany relationship, alongside trade and technology.

While the final contract is not expected to be signed immediately, high-level political engagement is seen as providing momentum. For India, the deal also diversifies defence partnerships beyond traditional suppliers, aligning with a broader foreign-policy objective.

The long-term impact on India’s naval posture

Once inducted, the six submarines will significantly strengthen India’s capacity for covert surveillance, sea denial and precision strikes. Just as important is the industrial legacy: a stronger domestic shipyard, a deeper supply chain, and a bridge toward future indigenous submarine designs.

Project-75I thus marks one of India’s most consequential naval decisions in years. Shaped by lessons from 1971, contemporary tensions with Pakistan, and China’s undersea expansion, it underscores how maritime power — silent, persistent and credible — is central to India’s evolving security strategy.