Rajnath Singh on Friday formally commissioned INS Aridhaman into the Indian Navy, marking a major advancement in India’s strategic deterrence capabilities. The submarine, also referred to as S4, is the third vessel in India’s indigenous nuclear-powered ballistic missile submarine (SSBN) programme, following INS Arihant (2016) and INS Arighaat (August 2024).
Its induction represents a significant strengthening of the naval component of India’s nuclear triad—the capability to deliver nuclear weapons from land, air, and sea. After successfully completing its final sea trials, INS Aridhaman is expected to be integrated into the Strategic Forces Command, which is responsible for managing India’s nuclear arsenal. The entire programme remains among the country’s most closely guarded defence initiatives.
Weighing approximately 7,000 tonnes, INS Aridhaman is slightly larger and more advanced than its predecessors. It features a refined and streamlined hull design aimed at enhancing stealth and reducing acoustic signatures, which are essential for survivability during underwater operations. The submarine is powered by an upgraded 83 MW pressurised water reactor developed by the Bhabha Atomic Research Centre, reflecting progress in India’s indigenous nuclear propulsion technology.
A major enhancement lies in its increased firepower. Unlike earlier submarines, INS Aridhaman is equipped with eight vertical launch tubes—twice the capacity of INS Arihant. This allows it to carry either up to eight K-4 missiles with a range of approximately 3,500 km or as many as 24 K-15 missiles with a range of around 750 km.
The addition of INS Aridhaman is expected to significantly improve India’s ability to maintain continuous at-sea deterrence, ensuring that at least one nuclear-armed submarine remains deployed at all times. This capability is central to a credible nuclear deterrence strategy, particularly in ensuring a reliable second-strike option.
India now joins a select group of nations—including the United States, Russia, the United Kingdom, France, and China—that operate nuclear-powered submarines. While the country has already established land- and air-based nuclear delivery systems, the expansion of its submarine fleet underscores a growing emphasis on strengthening its underwater nuclear capabilities.
Looking ahead, the Indian Navy is working on the next submarine in the series, referred to as S4*, along with the more advanced S5-class submarines. These future vessels are expected to be significantly larger, with an estimated displacement of around 14,000 tonnes, further enhancing India’s maritime and strategic strength.
The commissioning of INS Aridhaman aligns with India’s broader push toward defence self-reliance and indigenous capability, reinforcing its position as an emerging maritime power in a complex and evolving security landscape.
