Indian Navy's Submarine Shortfall Dilemma

Experts' worries intensified after Pakistan commissioned its first Chinese-built Hangor-class submarine, PNS Hangor, last month.

India last month bolstered the ship submersible ballistic nuclear (SSBN) arm of its nuclear triad by inducting the Arihant-class INS Aridhaman.

While this nuclear-powered, ballistic missile submarine secures the country's second-strike capability, the conventional diesel-electric submarine fleet presents a challenging picture.

The Indian Navy operates a fleet of conventional submarines comprising the Kalvari-class French-origin Scorpene, Russian-origin Kilo-class boats and German HDW submarines.

Several of these submarines are near decommissioning, raising concerns about India's underwater combat capability at a time when acquisition programmes are running late, China is increasing its presence in the Indian Ocean and Pakistan is modernising its navy.

The Indian Navy operates around 16 conventional diesel-electric submarines of different classes, according to "The Military Balance 2025" report by UK-based global think-tank International Institute for Strategic Studies.

Pakistan has five diesel-electric attack submarines (SSKs), including three Khalid-class (Agosta 90B) submarines equipped with air-independent propulsion (AIP) systems.

"We certainly don't have sufficient submarines. Whether these are in SSKs, which are diesel-electric submarines, or SSNs, which are conventionally armed but nuclear-propelled submarines, the only area where India currently has adequate numbers is in SSBNs," said Vice Admiral Pradeep Chauhan (retired), director-general of the New Delhi-based think-tank National Maritime Foundation.

Experts' worries intensified after Pakistan commissioned its first Chinese-built Hangor-class submarine, PNS Hangor, last month and the vessel was spotted in Malaysia en route to its base.

It is based on the Chinese Yuan-class design and is part of an eight-submarine deal between Beijing and Islamabad.

China Boosts Pakistan's Underwater Fleet

Four submarines for Pakistan's navy are being built in China and another four will be constructed at the Karachi Shipyard under a transfer-of-technology arrangement.

The Hangor-class submarines are expected to be equipped with advanced sensors, modern weapons and AIP technology, giving them significantly greater underwater endurance.

Conventional submarines need to surface or raise a snorkel to take oxygen and run their diesel engines to recharge on-board batteries.

AIP technology reduces this requirement, allowing submarines to remain submerged for much longer without frequent recharging, increasing their stealth and endurance by weeks, making them harder to detect.

This capability makes Pakistan the only country in South Asia currently operating AIP-equipped conventional submarines, while India works towards integrating the tech into its diesel-electric submarine fleet.

"The indigenous AIP being developed by the Defence Research and Development Organisation is in advanced stages of trials and is expected to be installed in the P75 (Project 75 for Kalvari-class submarines), as and when it is ready," Indian government sources said.

Navy's Submarine Gaps Remain Alarming

The case for the procurement of P75 (I) submarines, under a strategic partnership model, is also in the advanced stage of the procurement cycle.

The submarines will have AIP as part of the propulsion system, the sources added.

The Project 75 India programme to build six AIP-equipped diesel-electric attack submarines will succeed Project 75.

German company ThyssenKrupp Marine Systems is involved in P75 (I).

Experts said submarines are primarily used for sea denial, intelligence gathering and strategic deterrence rather than direct combat.

They warned that although comparing submarine numbers with China or Pakistan may not be fair, India's existing fleet remains inadequate for its operational requirements across the Arabian Sea and the wider Indo-Pacific.

"The shortfalls that have been allowed to develop in India's submarine arm are still alarming," Vice Admiral Chauhan said.

The Indian Navy has long sought to address the shortfall through a 30-year submarine construction programme, approved by the Cabinet Committee on Security in 1999, to induct 24 submarines in batches of six.

However, delays in procurement, technology transfer and slow implementation have left the navy under increasing operational strain as older vessels near retirement.

While the nuclear-powered submarine programme has gained momentum with the strengthening of India's sea-based nuclear deterrent, the conventional diesel-electric submarine or SSK arm continues to remain one of the navy's most significant capability gaps.

Feature Presentation: Aslam Hunani/Rediff