K-15 Sagarika (also known as B-05 or by its DRDO codename) is India’s first submarine-launched ballistic missile (SLBM), forming the sea-based leg of the K missile family and the primary armament of the Arihant-class SSBN fleet’s shorter-range strike option. As the missile that completed India’s nuclear triad when first fielded aboard INS Arihant, Sagarika occupies a foundational place in India’s strategic deterrent architecture.[1]
Development of the K-15 began in the late 1990s at DRDO’s missile complex in Hyderabad, with the specific goal of producing a submarine-launched ballistic missile compact enough to fit the vertical launch tubes of India’s then-developing Arihant-class nuclear submarines. The programme proceeded under considerable secrecy given its strategic sensitivity, with limited public confirmation of individual tests over the following decade.[2]
Sagarika measures approximately 10 metres in length and 0.74 metres in diameter, with an estimated mass of 6-7 tonnes, and can carry a nuclear warhead of roughly 1,000 kg to a range of around 750 km — a range that, as with the K-15 tubes aboard Arihant and Arighat, requires the launching submarine to patrol relatively close to an adversary’s coastline to hold key inland targets at risk.[1]
Sagarika/K-15 began integration testing with India’s lead nuclear-powered submarine during INS Arihant’s harbour trials, which commenced on 26 July 2009, well before the submarine’s eventual 2016 commissioning. The missile is carried in Arihant’s four vertical launch tubes, each capable of holding up to three K-15 missiles (or, alternatively, a single longer-range K-4 missile), giving submarine commanders flexibility in tailoring the strike loadout to mission requirements.[3]
The K-15 was reported as fully operationalised in August 2018, and in 2022 India’s Ministry of Defence confirmed a successful user training launch of the missile from INS Arihant, demonstrating the weapon’s continued operational readiness years after its initial fielding as part of routine crew training and validation exercises.[2]
Sagarika/K-15 is the shortest-range member of the broader K missile family of submarine-launched weapons, which also includes the substantially longer-ranged K-4 (approximately 3,500 km) and land-based derivative missiles such as Shaurya. As longer-range K-4 missiles have entered service aboard Arihant and Arighat, K-15 has increasingly been viewed by analysts as a shorter-range complement rather than the primary strike weapon, since K-4’s far greater range allows the same targets to be held at risk from much safer, farther-offshore patrol areas.[4]
As India’s first operational SLBM, Sagarika represented the critical missing piece that transformed India’s nuclear posture from a two-legged (land and air) deterrent into a genuine nuclear triad, providing the survivable, hard-to-detect second-strike capability considered essential to the credibility of India’s “No First Use” doctrine. Though now complemented by the longer-ranged K-4, Sagarika remains an active part of the Arihant-class weapons loadout and a foundational achievement in India’s underwater missile programme.[1]
| Type | Submarine-Launched Ballistic Missile (SLBM) |
| Country | India |
| Manufacturer | DRDO |
| Length | ~10 m |
| Mass | ~6-7 tonnes |
| Range | ~750 km |
| Payload | ~1,000 kg (nuclear) |
| Operationalised | August 2018 |
| Launch Platform | Arihant-class SSBN |
| Operator | Strategic Forces Command / Indian Navy |