K-4 (missile)

K-4 or Kalam-4 is a nuclear capable intermediate-range submarine-launched ballistic missile developed by the Defence Research and Development Organisation of India to arm its Arihant-class submarines. The missile has a maximum range of about 3,500 km which offers greater operational flexibility compared to its predecessor K-15 having a limited shore-bounding range. On deployment, the missile will be the first to operationalise India's sea-based nuclear triad and can accommodate the demand of credible second-strike capability of its nuclear doctrine.

The Arihant and Arighaat have four vertical launching system for the missile while Aridhaman and S4* submarines have double the number of vertical launching system. The latter three submarines will be equipped with K4 missiles while Arihant is equipped with B-05 missiles. The missile completed developmental launch trials and reportedly entered serial production after a final two consecutive launch trials in January 2020 within a gap of six days. On August 29, 2024, the missile was commissioned into the Indian Navy. In September 2024, ANI reported the deployment of the missile onboard the Arighaat, several days past her commissioning.