Three K-15s were successfully launched from the Arihant in August 2018. The K-15 Sagarika is a solid-fueled two-stage SLBM capable of carrying a single warhead and has a reported maximum range of 700 to 750 kilometers. It has been under development by India’s DRDO since the 1990s. Another test firing  of a K-15 SLBM from the INS Arihant took place in November 2015.

INS Arihant, the first and only operational SSBN, is armed with K-15 Sagarika missiles with a range of 750 km. It has a displacement of 6,000 tonnes and is powered by an 83 MW pressurised light-water reactor with enriched uranium. The K-4 will do away with the need to venture far way from the Indian waters and move closer to the adversary’s coast to launch the missile.

It is, however, unclear whether the Arihant’s launcher is capable of supporting the K-4 in operational configuration due to the 12-meter SLBM’s length and the 10.4-meter diameter of the SSBN’s hull, as Jane’s had pointed out in an April 2019 analysis. All subsequent tests were reportedly conducted from submerged pontoons.

There are very few countries which have managed to achieve this technological breakthrough. The Circular Error Probability (CEP) was much more sophisticated than Chinese missiles. The CEP determines the accuracy of a missile. The lower the CEP, the more accurate the missile is. The missile has been tested several times earlier as part of developmental trials to validate different parameters.

Once inducted, these missiles will be the mainstay of the Arihant class of indigenous ballistic missile nuclear submarines (SSBN) and will give India the stand-off capability to launch nuclear weapons submerged in Indian waters.