India’s second Arihant-class submarine, INS Arighaat, was commissioned into the Indian Navy on August 29, 2024, at Visakhapatnam in the presence of Defence Minister Rajnath Singh. In his address, the Defence Minister expressed confidence that Arighaat would further strengthen India’s nuclear triad, enhance nuclear deterrence, establish strategic balance and peace in the region, and play a decisive role in the nation’s security. He described it as a significant achievement for the country and a testament to the Modi-led government’s unwavering resolve to achieve ‘Aatmanirbharta’ in defence.

The Advent of INS Arighaat

The construction of INS Arighaat involved advanced design and manufacturing technology, detailed research and development, the use of special materials, complex engineering, and highly skilled workmanship. It is distinguished by its indigenous systems and equipment, which were conceptualised, designed, manufactured, and integrated by Indian scientists, industry, and naval personnel.

The technological advancements undertaken on this submarine make it significantly more advanced than its predecessor, INS Arihant. The presence of both INS Arihant and INS Arighaat will enhance India’s capability to deter potential adversaries and safeguard its national interests.

Strategic Significance of Submarines

Since the end of World War II in 1945, submarines have played a critical role on both strategic and tactical battlefields. From launching cruise missile strikes against high-value enemy assets to facilitating amphibious landings of special forces in hostile territories, attacking and sinking enemy warships, and even launching devastating nuclear strikes on enemy cities when required, a nation’s underwater military capabilities can tip the balance in its favour at the outset of war.

Thus, an undersea striking capability plays a crucial role in shaping a nation’s strategic doctrine. Submarines are often referred to as “Sharks of Steel” due to their ability to stealthily detect and instantly destroy targets.

India’s Nuclear Submarine Journey

With the growing battlefield requirements for precision strike weapons in theater-level warfare, the Indian Navy leased a nuclear-powered attack submarine (SSN) in 1987. Armed with cruise missiles and torpedoes, it was christened INS Chakra (K-43). The deal, struck with Russia, was for a 10-year lease.

Although Indian Navy personnel gained some first-hand operational experience in handling a nuclear-powered submarine, the benefits were limited, as the boat was partially manned by Russian sailors, and Indian crew members were not allowed access to the missile room or reactor compartment. The 10-year lease agreement was finally terminated by India in 1990, and the submarine was returned to Russia.

Future Capacity Build-up

While the indigenously developed nuclear-powered ballistic missile submarines (SSBNs) are being prepared for operational deployment, the first submarine of the Arihant series, INS Arihant, has already been inducted and deployed by the Indian Navy. The Arihant-class submarines are 112 metres long, with a beam of 11 metres, a draft of 10 metres, and a displacement of 6,000 tonnes. They have a diving depth of 300 metres and can accommodate around 95 naval personnel. These boats are powered by a single seven-blade propeller driven by an 83-megawatt (111,000 horsepower) pressurised water reactor fuelled by highly enriched uranium. They can achieve a maximum speed of 12–15 knots (22–28 km/h) when surfaced and 24 knots (44 km/h) when submerged. The submarines have four launch tubes in their hump and can carry up to 12 K-15 Sagarika ballistic missiles, each with a range of 750 km, or four K-4 ballistic missiles with a range of 3,500 km.

The second boat in the series, INS Arighaat, is now ready for combat patrols following its official induction. The third boat, INS Aridhaman, was quietly launched in November 2021 and may be inducted by 2025.

There are also indications that an Akula-class nuclear submarine may be leased from Russia for 10 years, allowing Indian sailors to gain more operational experience before the next generation of larger indigenous nuclear submarines (S-5-class) becomes operational.

While the Arihant-class SSBNs are nearing the final stages of sea trials and operational deployment, the Indian government is also looking ahead to Project-75 Alpha (also known as Project-77), which aims to procure new indigenously developed nuclear-powered attack submarines. The Cabinet Committee on Security (CCS) approved the construction of six such submarines in February 2015.

This new class of boats will be designed by the Indian Navy’s in-house Directorate of Naval Design (now Warship Design Bureau) and built at the Shipbuilding Centre in Visakhapatnam. Construction is expected to commence in 2024-25, with the first submarine entering service in 2032.

Time to Boost Nuclear Warhead Production

At a time when the Indian government, with its serious political will, is enabling the loading of MIRV (Multiple Independent Re-entry Vehicle) warheads on intercontinental ballistic missiles like the Agni-V, as demonstrated through Mission Divyastra on March 11, 2024, India must ramp up the production of active nuclear and thermonuclear warheads.

The Agni-VI, K-4, K-5, and K-6 ballistic missiles will also have MIRV capability. Therefore, India must be prepared to produce 400-500 nuclear warheads, instead of maintaining the current stockpile of 160-170 warheads. This will ensure an adequate number of nuclear and thermonuclear weapons in operational configurations for a credible second-strike capability during contingencies.

“India should definitely go ahead with the production of more nuclear warheads as we are stepping into the MIRV era. The 170-warhead stockpile cannot be designated as a credible minimum deterrence, especially at a time when questions have been raised about India’s capability to successfully test a hydrogen bomb,” says Bharat Karnad, a leading national security expert.

Time to Get Back to Work

As India’s hostile neighbours, China and Pakistan, undergo rapid military modernisation, the country has yet to witness significant levels of R&D and investments in strategic technologies. China possesses one of the largest submarine fleets, comprising between 68 and 85 boats across nine different classes, a far cry from the Indian inventory. Even Pakistan, which has a much smaller navy, has five conventional submarines, with an order for eight more from China.

While the Indian Navy requires a fleet of at least 30 submarines to counter a two-front war situation with Pakistan and China, the government needs to place greater emphasis on building more nuclear-powered ballistic missile submarines and nuclear-powered attack submarines. There is also an urgent need to operationalise the indigenous Air Independent Propulsion (AIP) system developed by DRDO for deployment on all future SSNs, SSKs, and SSBNs. The much-delayed K-5 and K-6 submarine-launched ballistic missile (SLBM) projects, with estimated ranges of 8,000 km and 12,000 km respectively, should be developed and tested at the earliest.

Additionally, there is a pressing need to develop an entirely new class of nuclear-powered ballistic missile submarines capable of launching intercontinental ballistic missiles. The proposed S-5 class of SSBNs, which will outweigh the Arihant-class boats and be capable of launching the next generation of K-6 nuclear missiles, will prove to be a significant force multiplier on the strategic battlefield.

Moreover, as countries like Japan research next-generation submarines (Soryu-class) powered by lithium-ion batteries, India should undertake similar initiatives and projects to ensure it remains at the forefront of cutting-edge technologies. Lithium-ion batteries are lighter and have a higher energy density, meaning they can hold more electricity per kilogram than traditional lead-acid batteries. They also hold their charge longer and recharge faster.

The ageing subsurface boats of the Indian Navy need to be replaced promptly, and newer weapon systems must be deployed soon. Submarines form the backbone of a nation’s blue-water naval capability, and the incumbent government cannot afford to compromise on this front.