INS Arighat, India's second ballistic missile submarine (nuclear-powered submarines armed with nuclear-tipped ballistic missiles or Ship Submersible Ballistic Nuclear (SSBN), could enter service by 2024, a new report says.

A report in the Hindustan Times has revealed that the indigenously-built boat is "expected to be commissioned latest by 2024".

The submarine is an upgraded variant of the only in-service SSBN INS Arihant. With a displacement of around 6,000 tons, the boat will be capable of carrying 12 K-15 submarine-launched ballistic missiles (SLBMs) or four K-4 SLMBs, apart from conventional torpedoes and mines.

While the K-15 has a range of 750 kilometres, the K-4 is capable of hitting targets as far as 3,500 kilometres away. Given its long range, the addition of K-4 missile to India's nukes delivery arsenal will allow India's SSBNs in the northern Bay of Bengal to target some parts of China.

Launched in 2017, the INS Arighat has been undergoing extensive trials.

India's SSBN Program

With the first two SSBNs ready, the focus has shifted to the slightly larger and better-armed boats — S4 and S4.

The two boats, the first of which was launched in 2021, are under construction at the Ship Building Centre in Visakhapatnam.

Satellite imagery has confirmed the reports of the S4 being slightly larger than INS Arihant and Arighat. The length of the boat could have been increased to make space for additional tubes for nuclear-tipped ballistic missiles. While INS Arihant has four vertical-launch missile tubes, the S-4 is reported to have at least eight tubes for nuclear missiles.

Consequently, S-4 will be able to carry eight K-4 SLBMs and 24 K-15 SLBMs, reportedly twice of what INS Arihant can be equipped with.

India is also working on a new series of SSBNs, which will be significantly more capable than the ones built before. The project is currently in the design phase. Identified as S-5, this new type of submarine will have a displacement of 13,500 tons, which is twice that of the Arihant-class boats, and capable of carrying 12 long-range nuclear-tipped missiles.

SSN Program In The Making

The government has also approved a program for the construction of nuclear-powered attack submarines or SSNs. The program involves the design and construction of six SSNs, each displacing around 6,000 tons.

Like SSBNs, SSNs are powered by a nuclear reactor and can remain underwater for long periods of time, much longer than diesel-electric submarines or SSKs, which have to surface at regular intervals to charge their batteries which power them under water.

At the same time, operating SSNs is not as complex as SSBNs as these boats are not armed with nuclear-tipped missiles.

Green light for this project was given in 2015, a year after the National Democratic Alliance (NDA) came to power. The initial design work had begun at the Gurgaon-based Submarine Design Centre sometime around 2017 and considerable progress has been made since.

In 2019, the government granted Rs 100 crore for the initial phase of development of these submarines.

With success in the initial design phase, the program has received clearance from the government for the detailed design phase.

The first SSN designed and built in India is expected to enter service with the Navy in the first half of the next decade.

INS Arihant: The Ghost of The Indian Ocean

Nuclear and diesel attack missile firing submarines are a very potent weapon in equatorial waters of the Indian Ocean as they are most difficult to detect due to the huge difference of temperature at the surface and in depth. Due to the large difference in temperature, a physical phenomenon called total internal reflection is caused because of which the submarine appears to be at a different place that where it actually is.