BY: Qaiser Bashir Makhdoom
*New Delhi, August 19, 2025* — The Indian Navy is poised to induct itsthird indigenously built nuclear-powered ballistic missile submarine(SSBN), *INS Aridhaman (S4)*, marking a significant leap forward in India’sstrategic naval capabilities. The vessel, launched in November 2021, hasbeen undergoing rigorous sea trials and is expected to join active servicelater this year Deccan Heraldlink).
*Enhanced Capabilities*INS Aridhaman, an upgraded variant of the Arihant-class, boasts a largerdisplacement—about 7,000 tonnes compared to 6,000 tonnes of itspredecessors—and features eight vertical launch system (VLS) tubes, doublethat of earlier vessels. Its Compact Light Water Reactor (CLWR) offersimproved stealth and endurance Defence News Indialink).
The submarine is capable of deploying a mix of up to 24 *K-15 Sagarika*missiles (range ~750 km), eight *K-4 SLBMs* (~3,500 km), or the moreadvanced *K-5 missiles* (~6,000 km)
*Strategic Deterrence Expanded *INS Arighaat, the second SSBN, was commissioned in August 2024 and alreadycarries K-4 missiles with a ~3,500 km range—significantly improving India’ssea-based deterrence over the earlier K-15 range of 750 km (ciss.org.pklink, The Times of Indialink).The upcoming INS Aridhaman, with its greater missile payload and improvedstealth, is expected to further solidify India’s second-strike capabilities
Developments are underway for the next-generation *S5-class SSBNs*,projected for production by 2027. These will be much larger (~13,500 t) andequipped with advanced K-6 missiles and reactors up to 190 MW——————————*Strategic Implications: Security Threat to Pakistan* *Sea-BasedSecond-Strike Capability*
The sustained introduction of SSBNs enhances India’s nuclear triad,providing credible and survivable second-strike capability. SSBNs, hiddenbeneath the ocean and mobile, are far less vulnerable to preemptivestrikes, enhancing deterrence posture (ciss.org.pklink,The Times of Indialink,*Extended Strike Range*
The K-4 missile’s ~3,500 km range enables Indian submarines to strike deepinto Pakistani territory from relatively safer maritime zones—such as theBay of Bengal or Indian Ocean—without entering contested waters (ciss.org.pklink,
A security-analysis article from Islamabad’s CISS highlights that:
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“The K-4 missile … can precisely target all of Pakistan and much ofChina” (ciss.org.pklink).
*Naval Asymmetry*
Pakistan currently lacks an SSBN capability. Its *Babur-3* SLBM, whilenuclear-capable, must be launched from conventional diesel-electric or AIPsubmarines, which are louder and more detectable, undermining theirsurvivability and second-strike reliability (ciss.org.pklink).*Infrastructure: Project Varsha*
India is building a dedicated SSBN base—*Project Varsha*—on the easterncoast, with underground pens to shelter and secure its submarine fleet,further bolstering survivability and readiness*Strategic Recalibration for Pakistan*
Pakistan may feel compelled to upgrade its naval nuclearposture—potentially seeking assistance from China to develop its own SSNsor SSBNs. Until then, its deterrence rests heavily on land- and air-basedsystems, which can be more vulnerable to a decapitation strike (ciss.org.pklink).——————————*Summary Table: Key Changes & Implications*Development Description & Impact*INS Aridhaman (S4)* 3rd Indian SSBN; larger, stealthier, with 8 VLS tubes;capable of K-4/K-5 missiles.*K-4 Missile* ~~3,500 km range SLBM; allows deep strikes from sea,enhancing submarine deterrence.*Naval Base (Varsha)* Protected eastern submarine base offering enhancedsurvivability of SSBNs.*Pakistan’s Gap* No SSBNs; limited by diesel subs; must rely on lesssurvivable second-strike means.*Strategic Shift* Forces Pakistan to consider countermeasures; risestension in strategic balance.——————————Final Thoughts
The upcoming induction of *INS Aridhaman* is more than a domesticmilestone—it marks a strategic inflection point in South Asia’s militarybalance. For Pakistan, it raises the stakes in maritime deterrence andnuclear survivability, forcing re-evaluation of posture, resourceallocation, and reliance on an increasingly imbalanced triangle of navalpower.