Pakistan Responds to Indian Submarine Threats with Full-Scale Coastal War Drills

(DEFENCE SECURITY ASIA) — The Pakistan Navy has launched a sweeping two-day maritime exercise across its coastal and port infrastructure, reinforcing its defensive posture against sub-conventional and asymmetric maritime threats—an imperative sharpened by a history of Indian submarines repeatedly attempting to breach Pakistan’s territorial waters.

Conducted between 1–2 June 2025, the exercise unfolded against the backdrop of a simmering military standoff between the nuclear-armed neighbours, following four consecutive days of cross-border hostilities involving precision airstrikes, ballistic missile launches, armed drone incursions, and sustained artillery exchanges along the Line of Control.

According to the Director General Public Relations for the Pakistan Navy, Commodore Ahmed Hussain, the exercise was specifically designed to “validate and refine tactics, techniques and procedures (TTPs) to ensure robust defence of critical maritime infrastructure against evolving asymmetric threats.”

“The exercise involved coordinated operations by PN (Pakistan Navy) Fleet units, Pak Marines, SSG (Navy), and Naval Aviation assets,” the Navy stated, highlighting the use of integrated operations across domains to confront increasingly unconventional warfare challenges.

Simulated threats included infiltration by enemy special forces, underwater sabotage, drone swarm attacks, and coordinated multi-domain assaults—scenarios directly relevant to current Indian naval doctrine emphasising network-centric warfare and maritime coercion.

These drills come just 48 hours after Indian Defence Minister Rajnath Singh delivered an aggressive warning that India would not hesitate to employ its naval firepower in response to “any future aggression by Pakistan,” a statement widely viewed as a signal of expanding naval posturing in the Indian Ocean Region (IOR).

In response, Pakistan’s military reiterated its firm commitment to safeguarding sovereignty and territorial integrity, referring to an earlier statement from May 12 that warned of a “comprehensive and decisive” response to any violation of its maritime boundaries.

Rear Admiral Faisal Amin, Commander Coast (COMCOAST), personally visited several operational stations during the exercise and observed live-action simulations, including port breach response and underwater threat interception drills conducted by the Navy’s Special Services Group and anti-sabotage teams.

In his remarks, Rear Admiral Amin praised the readiness levels and professionalism demonstrated by deployed forces and emphasized that the protection of port infrastructure—such as Gwadar and Karachi—is not just a matter of security, but a pillar of Pakistan’s economic resilience and energy corridor stability under CPEC.

“Pakistan Navy remains committed to maintaining a high state of readiness to respond to all forms of threats and continues to strengthen its capacity to defend the maritime frontiers against emerging challenges,” Commodore Hussain concluded.

This resolve was not rhetorical—Pakistan has a long history of intercepting Indian undersea assets attempting covert penetration of its territorial waters, with the latest such incident confirmed during Exercise SEASPARK-22 in March 2022.

During that 2022 incident, a Pakistan Navy anti-submarine warfare (ASW) unit successfully detected and tracked an Indian Kalvari-class diesel-electric submarine, which had attempted to enter Pakistan’s maritime zone under cover of war games and electronic silence.

The Indian submarine, operating on snorkel depth to recharge its lithium-ion batteries, was identified by Pakistan’s layered maritime domain awareness network, believed to include P-3C Orion aircraft, towed sonar arrays, and seabed hydrophone sensors.

“However, yet again through continuous vigilance and professionalism, Pakistan Navy has foiled Indian Submarine’s attempt of entering into Pakistani waters,” the ISPR said, noting that a rigorous monitoring protocol had been in place.

The statement added, “Strict monitoring watch and stringent vigilance procedures were enforced. Resultantly, the Pakistan Navy Anti-submarine warfare unit took the lead and prematurely intercepted and tracked the latest Indian submarine Kalvari.”

The 2022 incident marked the fourth confirmed interdiction of an Indian submarine by Pakistan since 2016, with previous attempts in October 2019 and November 2016, also repelled by long-range maritime patrol assets and coastal sonar networks.

The Kalvari-class submarines are diesel-electric attack submarines based on the French Scorpène-class design, constructed in India under Project-75.

These submarines are equipped with advanced stealth features, including acoustic silencing techniques and low radiated noise levels, making them difficult to detect.

They are armed with heavyweight torpedoes and SM.39 Exocet anti-ship missiles, enhancing their offensive capabilities.

The submarines also feature the SUBTICS combat management system, integrating all onboard sensors and weaponry for efficient operation.

The repeated incidents of underwater surveillance attempts suggest a broader undersea shadow war is unfolding between India and Pakistan, with implications extending well beyond regional rivalry and touching on global maritime stability across the Western Indian Ocean and Hormuz approaches.

Naval experts point out that with both nations actively expanding their submarine fleets—India through future Project-75(I) SSNs and Arihant-class SSBNs, and Pakistan via its acquisition of eight Chinese Type 039B Hangor-class SSKs—submerged confrontations are likely to grow in frequency and sophistication.

These evolving dynamics underscore the increasing need for robust command-and-control mechanisms, strategic restraint, and open lines of military-to-military communication to avoid inadvertent escalation in the maritime domain, where transparency is inherently limited.

As Pakistan signals its intent to harden its coastline and critical sea lanes against grey-zone operations, the recent exercise and Indian submarine incidents serve as a stark reminder that South Asia’s most dangerous flashpoint may now lie beneath the waves.

India’s submarine fleet represents the silent spearhead of the nation’s maritime deterrence posture, combining legacy Soviet platforms, modern French-origin diesel-electric boats, and a nascent but potent indigenous nuclear submarine capability.

With a mix of conventional and nuclear-powered assets, the Indian Navy’s submarine armada is structured to conduct multi-domain missions ranging from sea denial and anti-surface warfare to second-strike nuclear deterrence and ISR (intelligence, surveillance, reconnaissance) operations across the Indian Ocean Region (IOR).

As of mid-2025, the Indian Navy maintains a fleet of 17 submarines—comprising 15 diesel-electric attack submarines (SSKs) and two nuclear-powered platforms—positioning itself as a formidable undersea force in the Indian Ocean Region.

At the forefront of India’s conventional undersea capability are six Kalvari-class submarines, based on the French Scorpène design and built domestically under Project-75.

Five boats—INS Kalvari, Khanderi, Karanj, Vela, and Vagir—are operational, while the sixth, INS Vagsheer, is undergoing sea trials and is slated for commissioning by end-2025.

Armed with Exocet anti-ship missiles and heavyweight torpedoes, later Kalvari units are expected to incorporate air-independent propulsion (AIP), significantly enhancing endurance and stealth in littoral combat zones.

India also operates eight upgraded Kilo-class submarines—known locally as the Sindhughosh-class—sourced from Russia during the late 1980s to early 2000s.

Despite their age, ongoing mid-life refits and integration of Club-S cruise missiles have extended their relevance in strike and patrol roles.

Complementing these are four German-origin Type 209/1500 submarines, designated as the Shishumar-class, used primarily for training and coastal defence, with one unit recently undergoing life-extension upgrades.

India’s nuclear deterrent at sea is led by the Arihant-class SSBNs, forming the maritime leg of its strategic triad.

INS Arihant, operational since 2016, is armed with K-15 SLBMs (750 km range), while her successor, INS Arighat, is undergoing final outfitting and is expected to deploy K-4 SLBMs with extended reach up to 3,500 km.

For nuclear attack capability, India previously operated INS Chakra II, a leased Russian Akula-class SSN, which was returned in 2021.

Plans are underway to lease another Akula-class (Chakra III), while India concurrently develops six indigenous SSNs under a Strategic Forces Command program, intended to serve as the hunter-killer core of its future undersea fleet.

India’s next major leap—Project-75I—aims to acquire six advanced SSKs with AIP and vertical launch systems for BrahMos-class cruise missiles, though procurement delays continue.

Contenders include platforms from South Korea, Russia, Germany, and Spain, with final selection expected between 2025 and 2026.

Despite lagging behind China in numbers, India’s submarine fleet benefits from enhanced network integration, long-range maritime patrol aircraft (P-8I Poseidon), and growing indigenous production capability.

In a region marked by increasing Chinese naval assertiveness and Pakistani asymmetrical manoeuvres, India’s undersea fleet offers both credible deterrence and stealth-based force projection.

As tensions persist along the Line of Actual Control (LAC) and strategic competition deepens in the Indo-Pacific, India’s submarine force remains its most survivable instrument of maritime power and strategic messaging.

Meanwhile, as the geopolitical competition intensifies across the Indian Ocean Region (IOR), Pakistan is doubling down on its undersea warfare capabilities by modernizing its submarine fleet—quietly but decisively fortifying its sea-denial strategy and nuclear second-strike deterrent.

At the heart of Pakistan’s undersea warfare doctrine is a blend of French-designed legacy platforms and a new wave of modern Chinese submarines—collectively forming a credible, multi-layered force capable of surveillance, interdiction, and strategic deterrence across vital maritime chokepoints.

Currently, the Pakistan Navy operates five operational diesel-electric attack submarines (SSKs): three upgraded Agosta-90B (Khalid-class) boats with Air Independent Propulsion (AIP) systems, and two older Agosta-70 (Hashmat-class) submarines, which continue to serve primarily in training and support roles.

The Agosta-90B class, consisting of PNS Khalid, PNS Saad, and PNS Hamza, forms the operational core of Pakistan’s submarine fleet.

These vessels, displacing around 2,000 tonnes submerged, were constructed with French assistance in the late 1990s and early 2000s and are fitted with MESMA AIP modules, significantly extending their underwater endurance compared to traditional diesel-electric designs.

All three boats have undergone major mid-life upgrades under a $350 million deal with Turkey’s STM (Savunma Teknolojileri Mühendislik), integrating modern sonar systems, combat management suites, electronic warfare upgrades, new periscopes, and fire-control systems compatible with heavyweight torpedoes and submarine-launched cruise missiles.

Meanwhile, the Agosta-70 class, comprising PNS Hashmat and PNS Hurmat, commissioned in the late 1970s, still remains in service and are reportedly being used in secondary operational tasks and training capacities.

The centrepiece of Pakistan’s submarine modernization strategy, however, lies in the future induction of eight Hangor-class submarines, derived from the Chinese Type 039B (Yuan-class) design—a stealth-enhanced, AIP-equipped platform expected to redefine the regional undersea balance.

Under a 2015 agreement between Islamabad and Beijing valued at approximately $4–5 billion, four submarines are being built in China, while the remaining four are under construction at Karachi Shipyard & Engineering Works (KSEW) under a technology transfer deal.

As of 2025, the first two boats—PNS Hangor and PNS Shushuk—have already been launched at Chinese shipyards, with delivery expected by late 2025 and 2026, respectively.

These Hangor-class submarines, displacing approximately 2,800 tonnes, are reportedly configured to carry the Babur-3 submarine-launched cruise missile (SLCM)—a nuclear-capable system with an estimated range of 450 km, offering Pakistan a credible second-strike capability from underwater platforms.

Equipped with advanced passive/active sonar suites, integrated combat systems, and long-endurance AIP modules, the Hangor-class will allow the Pakistan Navy to maintain persistent undersea presence across the Arabian Sea and into the Strait of Hormuz.

This new generation of submarines will significantly augment Pakistan’s ability to conduct area denial operations, strategic ISR, and deterrent patrols deep within contested maritime spaces—particularly in response to Indian Navy deployments and joint exercises with QUAD nations.

In tandem, Pakistan continues to enhance its anti-submarine warfare (ASW) capabilities with P-3C Orion maritime patrol aircraft, unmanned undersea sensors, and expanding surface combatant networks to protect its own fleet and challenge enemy intrusion—especially in light of repeated Indian submarine detection incidents in 2016, 2019, and most recently in 2022.

Pakistan’s navy leadership has repeatedly underscored the strategic utility of submarines in safeguarding critical sea lanes and deterring hostile naval actions near Gwadar Port, which serves as a keystone of the China-Pakistan Economic Corridor (CPEC).

Given the rapid modernization of the Indian Navy’s own undersea force—including Kalvari-class (Scorpène) boats and an expanding nuclear fleet—Pakistan’s emphasis on indigenous construction, AIP technology, and strategic weapons integration reflects a deliberate shift toward survivability, autonomy, and technological parity.

By the end of the decade, the Pakistan Navy is expected to operate at least 11 modern submarines, most of them AIP-capable, making it one of the most formidable undersea forces in the region, especially in comparison to its relative size and conventional fleet limitations.

— DEFENCE SECURITY ASIA