Illustrative   
India's nuclear triad comprises sea-, land-, and air-based delivery systems for nuclear warheads, ensuring a credible second-strike capability under its "No First Use" policy. INS Aridhaman, as the third Arihant-class SSBN, forms the maritime pillar, providing the most survivable leg due to its stealthy underwater endurance.

India is poised to commission its third nuclear-powered ballistic missile submarine, INS Aridhaman, into the Indian Navy, marking a pivotal advancement in the nation's maritime nuclear deterrence. 

Scheduled for induction in April or May 2026, this stealthy vessel, codenamed S4, has successfully completed its final deep-sea trials.

With two operational Arihant-class submarines already in service—INS Arihant and INS Arighat—INS Aridhaman will significantly bolster India's sea-based second-strike capability under the Strategic Forces Command.

Constructed at the highly secretive Ship Building Centre in Visakhapatnam by Larsen & Toubro (L&T), a leading private sector firm, INS Aridhaman exemplifies India's Atmanirbhar Bharat initiative. 

Approximately 75 per cent of its components are indigenous, reflecting substantial progress in domestic defence manufacturing. After months of rigorous sea trials, the submarine is ready to join its predecessors, enhancing the Navy's strategic underwater fleet.

A key upgrade in INS Aridhaman is its vertical launch system (VLS), featuring eight missile tubes compared to the four in its elder siblings. This doubling of capacity allows it to carry up to eight K-4 submarine-launched ballistic missiles (SLBMs) with a range exceeding 3,000 km, or alternatively, 24 shorter-range K-15 Sagarika missiles with a 750 km reach. Such firepower extends India's deterrence envelope deep into adversarial territories.

The submarine's design prioritises stealth over speed, enabling it to operate silently at great depths where detection by conventional attack submarines becomes exceedingly difficult.

This 'ghost-like' presence is ideal for covert surveillance, intelligence gathering, and precision strikes during conflict. Operating from fortified bases like Project Varsha in the Bay of Bengal, it ensures a persistent at-sea deterrent.

INS Aridhaman's armament aligns seamlessly with India's "No First Use" nuclear policy, providing a credible survivable second-strike option. In an era of escalating tensions, particularly with China's rapid naval expansion in the Indo-Pacific, this platform guarantees retaliation even if land-based assets are compromised. Its long-range K-4 missiles can target threats across vast distances, reshaping regional power dynamics.

By introducing doubled missile tubes and enhanced stealth, INS Aridhaman redefines India's strategic posture in the Indo-Pacific. It counters the numerical superiority of rival fleets, particularly from the People's Liberation Army Navy, through assured continuous underwater patrols. This induction not only strengthens maritime security but also signals India's resolve to maintain equilibrium amid geopolitical flux.

INS Arihant and INS Aridhaman represent successive steps in India's Arihant-class nuclear-powered ballistic missile submarines (SSBNs), with Aridhaman (S4) featuring notable upgrades over the lead boat.

FeatureINS Arihant (S2)INS Aridhaman (S4)
Displacement (Surfaced)~6,000 tons~6,000-7,000 tons (Larger Hull)
Length~110-115 metres ​~130 Metres
Missile Tubes (VLS)4 tubes ​8 tubes (Doubled Capacity)
Missile CapacityUp to 12 K-15 (750 km) or 4 K-4 (>3,000 km)​Up to 24 K-15 or 8 K-4 Units
Reactor Power83 MW PWR ​83 MW CLWR-B1 PWR (Enhanced)
​Speed (submerged)~24 knots ​~24 knots
​Crew~95 ​~95-100
​Indigenous ContentLower (~50-60%) ​~75%
Commissioning2016 ​Expected Apr-May 2026
Key UpgradesPrototype Design ​Stealth, Sonar (USHUS/Panchendriya), Size

Aridhaman's expanded hull and VLS enable greater firepower for second-strike deterrence, aligning with India's nuclear triad goals. Both operate under Strategic Forces Command from Visakhapatnam bases.

The arrival of INS Aridhaman underscores the maturation of India's nuclear triad, with sea-based assets now forming a robust pillar alongside air and land vectors. As the Indo-Pacific emerges as a theatre of great-power competition, this submarine's capabilities will deter aggression, safeguard sea lanes, and underpin regional stability.

IDN (With Agency Inputs)