India's Second Nuclear Submarine, INS Arighaat, Enters Service - Four Things You Should Know

India has commissioned its second ballistic missile nuclear submarine (SSBN) — INS Arighaat — in a ceremony that took place in Vishakhapatnam today.

Unlike nuclear-attack submarines (SSNs), which are powered by nuclear reactors but carry conventional, non-nuclear weapons, SSBNs like Arighaat are equipped with ballistic missiles armed with nuclear warheads. Arighaat, like its predecessor INS Arihant, is expected to weigh close to 6,000 tonnes and measure over 111 meters in length. Both submarines are powered by an 83 MWe pressurised nuclear reactor, designed, developed, and manufactured by the Bhabha Atomic Research Centre with consultancy from Russia.

Here are four key things you should know about INS Arighaat:

1. More Advanced than INS Arihant

INS Arighaat, the government has officially acknowledged, is a significant step forward from its predecessor, INS Arihant, which was inducted in August 2016.

The eight-year gap before the induction of Arighaat has allowed for numerous upgrades and advanced equipment to be incorporated. While the external design of Arighaat remains similar to that of Arihant, several design modifications, based on operational experience with Arihant, make Arighaat more advanced.

2. Strengthening India's Deterrent Posture

With Arighaat's commissioning, India’s nuclear deterrent posture becomes even more robust. While INS Arihant completed the nuclear triad, Arighaat enhances it by providing a constant and credible second-strike capability. Given India’s no-first-use (NFU) doctrine, the ability to maintain a patrolling submarine ready to launch a nuclear strike at short notice is critical. Arighaat ensures that even if one submarine is undergoing maintenance, another remains on patrol, ready to retaliate.

3. Long-Range Patrol in the Indo-Pacific

Following its commissioning, Arighaat is expected to embark on a long-range patrol in the Indo-Pacific, Hindustan Times has reported.

This marks a significant milestone as it could be the first time an Indian SSBN armed with ballistic missiles undertakes such a mission. Unlike its predecessor, which primarily patrolled the Bay of Bengal, Arighaat’s long-range patrol reflects the growing confidence of the Indian Navy and Ministry of Defence in its capabilities. It also sends a clear message to adversaries about the maturity of India's deterrent force.

4. Twelve K-15 or Four K-4 Nuclear-Capable Ballistic Missiles

INS Arighaat has the capability to carry either twelve K-15 or four K-4 ballistic missiles, all of which are capable of carrying nuclear warheads. From its position in the northern Bay of Bengal, Arighaat can strike some Chinese targets. In addition to ballistic missiles, the submarine is equipped with six 533mm torpedo tubes and can carry between 18 and 30 torpedoes, further enhancing its combat capabilities.