India’s fourth nuclear submarine launched into water

Vice Chief of the Indian Navy Vice Admiral Krishna Swaminathan (Right) addresses a press conference, in New Delhi on October 22, 2024.
| Photo Credit: Sushil Kumar Verma

India’s fourth nuclear-powered ballistic missile submarine (SSBN), referred to as S4*, was launched into water at the Ship Building Centre in Visakhapatnam last week, official sources confirmed. This submarine is bigger and more capable than the first, INS Arihant (S2), which is essentially a technology demonstrator developed under the Advanced Technology Vessel programme.

The S4* was launched into water on October 16 at SBC, multiple sources confirmed. It has significant indigenous content, with Indian industry being extensively involved, according to a source.

India currently has two SSBNs operational. INS Arihant was quietly commissioned into service in August 2016. It has a displacement of 6,000 tonnes and is powered by an 83 MW pressurised light-water reactor with enriched uranium. The second SSBN, INS Arighaat (S3), which retains the same reactor and dimensions with several technological upgrades, was commissioned end-August. The 3rd SSBN Aridhman (S4) is currently undergoing sea trials and is expected to be commissioned, into service next year, sources said.

Responding to questions on the launch at a press conference on Tuesday (October 22, 2024), Vice Chief of the Navy, Vice Admiral Krishna Swaminathan, without directly commenting, said, “The SSBN programme is a successful one. Two submarines have been commissioned, and it is natural that others will follow.”

The first two SSBNs share the same reactor, while the S4 and S4* have an improved reactor, another source said. The S4* is bigger and can carry a number of the K-4 submarine launched ballistic missiles (SLBM), sources added.

Earlier this month, the Cabinet Committee on Security approved the construction of two indigenous nuclear attack submarines (SSN), also called hunter-killers, a critical requirement for the Indian Navy to monitor the Indo-Pacific.

The completion of the nuclear triad was announced in November 2018, when Prime Minister Narendra Modi announced on social media that INS Arihant had returned from its first deterrence patrol. The ATV project began in the 1980s, and Arihant was launched in 2009 by then Prime Minister Dr. Manmohan Singh.

INS Arihant is presently armed with a 750km range K-15 SLBM. The S4* carries the advanced 3,500 km range SLBM K-4 that was tested for the first time in 2020. The K-4 will be the mainstay of India’s undersea nuclear deterrence as it provides standoff capability to launch nuclear weapons while submerged in Indian waters until a 5,000 km range SLBM is developed and fielded.

A robust, survivable, and assured retaliatory capability is in line with India’s policy to have ‘Credible Minimum Deterrence’ (CMD) that underpins its ‘No First Use’ commitment. In 1998, India conducted nuclear tests under Phokran-II, and in 2003, India declared its nuclear doctrine based on CMD and a NFU policy while reserving the right of massive retaliation if struck with nuclear weapons first.