India has achieved a major strategic milestone by successfully test-firing its K-4 intermediate-range ballistic missile from the nuclear-powered submarine INS Arighaat.
The trial took place in the Bay of Bengal off the coast of Visakhapatnam. The K-4 missile, which is solid-fuelled and capable of carrying a two-tonne nuclear payload, was tested to its full operational range of 3,500 kilometres. This successful launch from the 6,000-tonne INS Arighaat, which was commissioned on 29 August 2024, significantly bolsters the sea-based leg of India’s nuclear triad.
The test was conducted by the tri-service Strategic Forces Command to validate the weapon's integration with its underwater platform. While land-based Agni-5 missiles and air-delivered bombs provide robust deterrence, submarine-launched ballistic missiles (SLBMs) are considered the most survivable platforms for a retaliatory strike under India's "no first-use" policy.
This development helps narrow the capability gap with global powers like the US, Russia, and China.
India's secretive Advanced Technology Vessel (ATV) programme, valued at over £8.5 billion (Rs 90,000 crore), continues to expand. Following the 2018 operational status of INS Arihant, the navy plans to commission a third submarine, INS Aridhaman, in early 2026, followed by a fourth in 2027. Future plans include 13,500-tonne vessels equipped with 190 MW reactors and K-6 missiles capable of reaching 6,000 kilometres.