The 3,500-km range missile, designed for the Arihant class of nuclear submarines, will be tested from a fixed underwater pontoon as part of the developmental trials being conducted by the Defence Research and Development Organisation (DRDO). The K-4 has undergone three tests in the past and is considered to be the real game changer that would give India a second strike option

by Manu Pubby

NEW DELHI: India is set to test fire its most potent nuclear deterrence missile over this weekend in the Bay of Bengal, which will demonstrate a survivable second strike capability to target all potential adversaries. The test of the K4 submarine-launched nuclear capable missile is scheduled to take place from the eastern coast, provided the weather holds up, sources told ET.


The 3,500-km range missile, designed for the Arihant class of nuclear submarines, will be tested from a fixed underwater pontoon as part of the developmental trials being conducted by the Defence Research and Development Organisation (DRDO).

If the test goes through—an earlier window in November had to be cancelled as cyclone Bulbul hit the eastern coast—it would mark a significant step towards operationalising the nuclear capable missile. The last test of the K4 was attempted in 2017 and there has been an urgency to expedite the developmental process, given that India’s second nuclear submarine, the INS Arighat, is nearing completion and would be ready for trials soon.


India has already notified seafarers and sent out a notice to airmen blocking a flight path of close to 3,000 km that stretches to the Indian Ocean in preparation for the test. The K-4 has undergone three tests in the past and is considered to be the real game changer that would give India a second strike option.

While India does have an operational SLBM (the K-15) on-board the INS Arihant, its range is capped at 750 km, limiting second strike options and with that, the effectiveness of the nuclear triad. Though land-based Agni series of missiles have proved their worth with multiple tests over the past years and India has its Mirage-2000 fighters rigged to deliver strategic warheads, an underwater launched missile is widely considered to be the most potent second strike weapon.

Given India’s no first use policy, the only time the country would launch strategic weapons would be if it comes under a nuclear strike from an adversary. In this situation, a submarine that is hidden deep in the sea, with the ability to target all potential enemies is considered to be the most effective tool. DRDO has also started work on the K-5, a 5,000 km range SLBM that would be fitted on-board nuclear powered submarines as well, to match the range of the Agni V, India’s longest range land-based missile.

A successful integration of the K-5 would demonstrate that India has a credible triad in place – the ability for a strike by land, sea or air.

The most recent landmark on the strategic front was the first deterrence patrol by INS Arihant that was carried out in November last year.