The submarine, while currently armed with the K-4 missile capable of striking targets up to 3,500 kilometres away, is being readied for the next leap in capability with the K-5 submarine-launched ballistic missile.

Testing of the K-5 missile, including preliminary “pop-up” launches and full-range trials, is expected to begin between late 2026 and early 2027. To accommodate this new class of weapon, the INS Aridhaman and the forthcoming S4* submarine have undergone significant physical modifications.

Unlike the earlier INS Arihant and INS Arighaat, which displaced around 6,000 tons and were constrained by smaller hulls and launch bays, the S4 features a stretched 7,000-ton hull. This expanded design provides the depth and structural resilience required to house the larger three-stage ballistic missiles intended for intercontinental missions.

The K-5 missile represents a dramatic technological advance over its predecessor. While the K-4 is a two-stage, solid-fuelled missile designed for regional deterrence, the K-5 employs a three-stage solid-fuelled system that extends its range to an estimated 5,000 to 6,000 kilometres.