India’s fourth nuclear missile submarine with 75 percent indigenous content launched – here’s all about it

India this week quietly launched its fourth nuclear-powered ballistic missile submarine (SSBN) at the Ship Building Center (SBC) in Visakhapatnam, boosting its nuclear deterrent capabilities.

This launch follows the commissioning of the second SSBN, INS Arighat, by Defense Minister Rajnath Singh on August 29, 2024. The third SSBN, INS Aridhaman, will be commissioned next year.

On October 9, the Cabinet Committee on Security (CCS) approved the construction of two more nuclear-powered attack submarines to strengthen India’s presence in the Indo-Pacific.

While the Modi government has been discreet about its nuclear deterrent strategy, the fourth SSBN, codenamed S4*, was launched on October 16, just a day after Defense Minister Singh inaugurated a very low frequency naval station in Vikarabad, Telangana, designed for communication with the strategic assets of the Indian Navy.

The newly launched S4* submarine has almost 75 percent indigenous content and is equipped with K-4 ballistic missiles, which have a range of 3,500 km and are fired via vertical launch systems.

While the first SSBN, INS Arihant, carries K-15 nuclear missiles with a range of 750 km, its successors, including S4*, are equipped exclusively with K-4 missiles. These submarines have virtually unlimited range and endurance, with operational limits determined only by food supply, crew fatigue and maintenance needs.

INS Arihant and INS Arighat already conduct deep-sea patrols, and India is expected to lease a Russian nuclear-powered Akula-class attack submarine in 2028. At the same time, the sixth Kalvari-class diesel-electric submarine, INS Vagsheer, is expected to be commissioned in December this year.

India’s SSBNs are critical to its strategy against adversaries like China as aircraft carriers become increasingly vulnerable to Chinese long-range missiles such as the Dong Feng-21 and Dong Feng-26. Consequently, the government has prioritized nuclear submarines over the Indian Navy’s third aircraft carrier.

In addition, there are plans to build three advanced diesel attack submarines in partnership with the French Naval Group, with the aim of strengthening India’s defenses in the Indian Ocean Region (IOR) as PLA warships increasingly patrol the area.