Beneath The Waves, India Secretly Tested A Nuclear Capable Ballistic Missile That Can Cover Pakistan, Parts Of China – K-4 Revealed

On December 23, 2025, India silently carried out a submarine-launched ballistic missile test in the Bay of Bengal. The missile is believed to be the nuclear-capable K-4 with a range of around 3,500 km, launched from an Arihant-class submarine. The test further strengthens India’s sea-based nuclear deterrent.

New Delhi: India carried out a covert test of a submarine-launched ballistic missile (SLBM) in the Bay of Bengal on December 23. It adds another layer to the country’s strategic deterrence at sea. According to sources, the missile tested was the nuclear-capable K-4, which was launched from an Arihant-class nuclear submarine INS Arighaat.

The test was not publicly announced. Notices to Airmen (NOTAMs) linked to the test area were withdrawn to maintain secrecy, especially as Chinese surveillance vessels were reported to be operating in the region at the time. So far, there has been no official confirmation from the Ministry of Defence, the Defence Research and Development Organisation (DRDO) or the Indian Navy.

Strategic experts see the test as a decisive step in reinforcing India’s sea-based nuclear triad, a cornerstone of credible second-strike capability. In practical terms, this ensures that even if India were to face a first strike, it would retain the ability to respond decisively from the sea.

The K-4 missile belongs to India’s indigenous K-series, developed by the DRDO specifically for deployment on Arihant-class nuclear-powered ballistic missile submarines. The K-4 has an estimated range of about 3,500 kilometres, with some assessments putting it between 3,000 and 4,000 kilometres depending on the payload. This is a major jump from the earlier K-15 missile, which could reach only around 750 kilometres.

The missile is around 12 metres long, with a diameter of about 1.3 metres and weighs roughly between 17 and 20 tonnes. It can carry a payload of up to two tonnes, including a nuclear warhead. Powered by a two-stage solid-fuel rocket, the K-4 is designed for underwater “cold launch”, can perform three-dimensional manoeuvres and is built to complicate interception by ballistic missile defence systems.

Arihant-class submarines are understood to be capable of carrying four K-4 missiles each, while future submarines in the series are expected to carry up to eight. The missile had earlier been successfully tested from INS Arighat in November 2024, indicating progress toward operational readiness. From a strategic standpoint, the K-4 is meant purely as a deterrent and fits within India’s stated “No First Use” nuclear doctrine.

Launched from the Bay of Bengal or deeper stretches of the Indian Ocean, its range comfortably covers all of Pakistan, including Islamabad, Karachi and Lahore. It also brings large parts of southern and central China within reach, including regions around Beijing, Shanghai, Guangzhou, Chengdu and Tibet, with some northeastern areas of China also falling within its envelope.

Defence analysts say such tests highlight India’s growing self-reliance in critical strategic technologies and enhance the credibility of its nuclear deterrence. They add that strengthening sea-based capabilities contributes to long-term regional stability by reinforcing deterrence rather than signalling intent for use.