India’s underwater nuclear deterrence is set to receive a significant enhancement with the impending dual induction of the INS Aridhaman (S4) and its sister vessel, S4*, by early 2027. Both submarines, developed under the Advanced Technology Vessel project, showcase advanced engineering with increased missile capacity and improved stealth capabilities, featuring an 83 MW Pressurized Water Reactor. The timely commissioning of these 7,000-tonne submarines is crucial for maintaining India’s credible minimum deterrence amid rising tensions in the Indo-Pacific region, particularly regarding China’s maritime assertiveness and Pakistan’s submarine advancements. With S4 and S4* operational, India’s SSBN fleet will expand to four, paving the way for future enhancements and reinforcing strategic deterrence against potential adversaries.