India has successfully test-fired its K‑4 submarine-launched ballistic missile (SLBM) from the nuclear-powered submarine INS Arighaat in the Bay of Bengal. The missile, with a range of 3,500 kilometres, represents a major step forward in strengthening India’s sea-based nuclear deterrence.
The launch was conducted under the supervision of the Strategic Forces Command. Defence analysts describe it as a significant move in boosting India’s “second-strike” capability, ensuring that the country retains the option to respond even if faced with a nuclear attack. The test underlines India’s progress toward operationalising a credible nuclear triad – the ability to deploy nuclear weapons from land, air, and sea.
Developed by the Defence Research and Development Organisation (DRDO), the K‑4 missile is a solid-fuel, intermediate-range weapon. It can carry a nuclear warhead of up to 2.5 tonnes. Designed for underwater launch, the missile exits the submarine, rises through the water, and then ignites its rocket motor to reach distant targets.
Previously, India’s submarines carried K‑15 missiles with a shorter range of around 750 km. The K‑4 dramatically extends the reach of India’s sea-based strategic forces, allowing for more flexible deployment and greater deterrence.
INS Arighaat, commissioned in August 2024, is India’s second nuclear-powered ballistic missile submarine. Its integration with the K‑4 missile marks a key milestone in strengthening the operational readiness of India’s strategic submarine fleet.
Although the Defence Ministry has not released an official statement, analysts say the test signals India’s growing strategic capabilities. With this achievement, India joins a small group of countries capable of firing long-range nuclear missiles from submarines, enhancing regional security posture and deterrence.
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