This milestone reflects India’s maturing nuclear triad, though full CASD capability will only be realised once all four Arihant-class SSBNs are operational and the larger S5 class enters service.
India’s expanding fleet of nuclear-powered ballistic missile submarines demonstrates its commitment to credible second-strike capability. The commissioning of INS Aridhaman at Visakhapatnam was not officially confirmed by New Delhi, but satellite imagery from 5 April 2026 revealed celebratory maritime signal flags, corroborating reports of its induction.
The submarine joins INS Arihant and INS Arighaat, while the fourth SSBN, S4*, expected to be named INS Arisudan, is undergoing sea trials following its launch in October 2024.
Despite progress, India’s SSBN fleet is not yet fully operational in a CASD role. Imagery from January 2026 showed all four hulls docked at Visakhapatnam, highlighting the challenges of sustaining continuous patrols.
With three boats, a rotation between patrol, repair, and training is possible but leaves little redundancy. Commissioning S4* in 2027 will ease operational pressures, enabling at least one submarine to remain on patrol while others cycle through maintenance and training. This structure suggests India is preparing for CASD, though some analysts argue that only the forthcoming S5 class will provide undeniable robustness.
The Arihant-class submarines reflect India’s evolving design philosophy. The first two boats, Arihant and Arighaat, were limited to four vertical launch tubes, initially armed with short-range K-15 Sagarika SLBMs.
These missiles, with a range of 700 km, restricted patrol areas and targeting options. The development of the 3,500 km-range K-4 missile addressed these limitations. The latter two boats, Aridhaman and S4*, feature eight vertical launch tubes, requiring longer hulls and increased displacement, thereby enhancing missile capacity and operational flexibility.
India’s SSBN program is complemented by infrastructure developments. Visakhapatnam has long hosted the fleet, but its congested port environment poses security challenges. To address this, India has been constructing INS Varsha, a secure base located 50 km south of Visakhapatnam.
Project Varsha includes underground submarine pens and tunnels, designed to conceal deployed numbers from satellite surveillance and provide natural protection. Satellite imagery shows two large tunnel entrances, 1.5 km apart, with water inside, indicating near completion.
The facility is expected to accommodate up to 12 nuclear submarines, including the next-generation S5 class, and will serve as the principal support base for India’s SSBN fleet.
INS Varsha’s strategic significance lies in its ability to enhance survivability and concealment, countering China’s advanced submarine facilities such as those at Hainan Island. Its proximity to BARC Atchutapuram ensures access to nuclear infrastructure, while its location enables rapid deployment to key chokepoints like the Strait of Malacca. The base strengthens India’s deterrence posture in the Indian Ocean Region, providing resilience against adversary surveillance and strike capabilities.
India’s SSBN development has been a long journey, beginning in the 1970s with plans for nuclear-powered attack submarines. Following nuclear tests in 1998, India’s nuclear doctrine outlined the need for a triad, leading to the adaptation of SSN designs into SSBNs.
The commissioning of Aridhaman represents the culmination of decades of effort, though India’s deterrence remains a work in progress. The rollout of Very Low Frequency communications systems and the gradual implementation of CASD will be critical to achieving a credible minimum deterrence posture.
Political considerations also influence SSBN deployments. While Arihant was deployed during the 2019 Pulwama–Balakot crisis, SSBNs were absent from reports during the May 2025 crisis, reflecting deliberate nuclear signalling choices by Indian leaders. Such decisions underscore the interplay between operational readiness and strategic messaging.
The commissioning of INS Aridhaman is therefore both a technological and strategic milestone. It enhances India’s survivability, expands missile capacity, and strengthens its nuclear triad. Yet, the journey towards full CASD capability continues, with INS Varsha and the S5 class submarines set to play pivotal roles in the coming decade.
Agencies
