India’s Defence Minister, Rajnath Singh, officially commissioned the domestically constructed nuclear-powered ballistic missile submarine (SSBN) INS Aridhaman into the Indian Navy, marking a significant advancement in the nation’s strategic deterrence capabilities. INS Aridhaman, also known as S4, is the third vessel in India’s indigenous SSBN program, following the introduction of INS Arihant in 2016 and INS Arighaat in August 2024. This event underscores India’s progress in fortifying the naval component of its nuclear triad, which enables the deployment of nuclear weapons via land, air, and sea.
After successfully completing its final sea trials, INS Aridhaman is poised to join the Strategic Forces Command, responsible for overseeing India’s nuclear arsenal. The submarine’s integration into the fleet represents a pivotal development in one of the nation’s most confidential defense initiatives.
Weighing approximately 7,000 tonnes, INS Aridhaman surpasses its predecessors in size and features a streamlined hull design aimed at enhancing stealth and acoustic performance, crucial for underwater operations. The vessel is propelled by an upgraded 83 MW pressurized water reactor (PWR) developed by the Bhabha Atomic Research Centre (BARC), showcasing India’s expanding expertise in indigenous nuclear propulsion technology.
A significant enhancement in INS Aridhaman’s capabilities lies in its firepower, as it is equipped with eight vertical launch tubes, doubling the missile capacity of INS Arihant. This configuration allows the submarine to carry either up to 8 K-4 ballistic missiles with a range of about 3,500 km or as many as 24 K-15 missiles with a range of around 750 km.
The commissioning of INS Aridhaman is anticipated to bolster India’s capacity for maintaining continuous at-sea deterrence, ensuring the presence of at least one nuclear-armed submarine on patrol at all times—a critical aspect of a credible nuclear deterrence strategy. India joins a select group of nations, including the US, Russia, the UK, France, and China, in operating nuclear-powered submarines.
As India has already demonstrated land- and air-based nuclear capabilities, the expansion of its submarine fleet underscores a strategic focus on reinforcing its underwater nuclear capabilities. The Indian Navy is actively developing the next submarine in the series, referred to as S4*, along with the more advanced S5-class submarines, which are expected to be notably larger with an estimated displacement of around 14,000 tonnes.
The commissioning of INS Aridhaman aligns with India’s broader objective of achieving defense self-sufficiency and bolstering indigenous military capabilities, cementing its status as an emerging maritime power in an increasingly intricate security landscape.