INS Aridhaman to Boost India’s Sea-Based Nuclear Deterrent

India is set to strengthen its sea-based nuclear deterrent with the commissioning of INS Aridhaman, the third indigenous Arihant-class nuclear-powered ballistic missile submarine (SSBN). The submarine, designated S4, is expected to be inducted into the Indian Navy by April-May after completing final stages of sea trials.

Once commissioned, it will mark a significant milestone in India’s quest for credible and continuous at-sea nuclear deterrence.

Advanced Capabilities of INS Aridhaman

Built under the Advanced Technology Vessel (ATV) project at the Ship Building Centre in Visakhapatnam, INS Aridhaman displaces around 7,000 tonnes, making it larger than its predecessors INS Arihant and INS Arighaat, which are 6,000-tonne platforms.

The submarine will be armed with 24 K-15 Sagarika submarine-launched ballistic missiles (SLBMs) with a range of 750 km and eight longer-range K-4 SLBMs capable of striking targets up to 3,500 km away. Powered by an 83 MW pressurised water reactor, it features improved acoustic damping through anechoic tiles to reduce detectability.

Strengthening Second-Strike Capability

As a stealthy underwater platform, INS Aridhaman enhances India’s “second-strike” capability — the assured ability to retaliate after absorbing a nuclear attack. With three operational SSBNs under the Strategic Forces Command, India moves closer to achieving Continuous At-Sea Deterrence (CASD), ensuring at least one nuclear-armed submarine remains on patrol at all times.

The submarine is expected to be based at Project Varsha near Visakhapatnam, a high-security naval facility with underground pens designed for strategic assets.

Broader Submarine Modernisation Drive

India’s undersea expansion also includes the planned induction of an Akula-class nuclear-powered attack submarine (SSN) from Russia, commonly referred to as Chakra III, likely by 2027 or early 2028. Simultaneously, negotiations with Germany are in advanced stages for the $8–10 billion Project-75(I) programme to construct six advanced diesel-electric submarines equipped with Air-Independent Propulsion technology.

These developments come amid regional naval modernisation, including Pakistan’s acquisition of eight Hangor-class submarines from China.

Important Facts for Exams

• Arihant-class submarines form the sea-based leg of India’s nuclear triad.
• K-4 SLBM has a reported range of around 3,500 km.
• Continuous At-Sea Deterrence ensures at least one SSBN on patrol year-round.
• Project-75(I) aims to build six advanced conventional submarines with AIP.

Advancing the Nuclear Triad

With INS Aridhaman nearing commissioning, India’s nuclear triad — comprising land-based missiles, air-delivered systems and sea-based deterrents — gains further depth. The induction signals progress in indigenous submarine-building capability and reinforces India’s long-term strategic deterrence posture in the Indo-Pacific region.