India on Tuesday successfully carried out a test of its intermediate-range submarine-launched ballistic missile K-4 from the nuclear-powered submarine INS Arighaat, further strengthening the country’s sea-based strategic deterrence. The launch was conducted in the Bay of Bengal, off the coast of Visakhapatnam, as part of routine validation of India’s undersea nuclear strike capability.
With a strike range of around 3,500 kilometres, the K-4 significantly enhances the reach of India’s naval nuclear forces. The missile is designed for deployment on Arihant-class ballistic missile submarines, allowing them to carry out deterrence patrols while remaining concealed deep underwater for extended durations. Defence officials view this capability as a key component of India’s assured second-strike posture.
The K-4 was commissioned into the Indian Navy in August 2024, placing India among a small group of countries that possess operational nuclear delivery systems across land, air and sea platforms. The missile has been developed from the land-based Agni-III system, with modifications enabling cold launch from a submerged platform before ignition in the air.
Capable of carrying a nuclear warhead weighing up to 2.5 tonnes, the K-4 represents the most discreet leg of India’s nuclear triad. The ‘K’ series of missiles is named in honour of APJ Abdul Kalam, reflecting his contribution to India’s missile development programme.
