INS Arighat joins Navy: How will SSNs, SSBNs transform India's defence?

Typically smaller and more agile, SSNs are optimised for speed and manoeuvrability, while SSBNs are larger, and designed to carry and launch SLBMs from vertical launch systems

In a notable advancement for India's nuclear deterrence, the Indian Navy welcomed its second nuclear-powered ballistic missile submarine, INS Arighat, into service last week. The induction ceremony, held in Visakhapatnam, Andhra Pradesh, saw the presence of Defence Minister Rajnath Singh, who highlighted that this addition strengthens India's nuclear triad and overall deterrence capabilities. Though more advanced than its predecessor, the INS Arighat is part of the Arihant-class submarines, named after the Sanskrit term that translates to 'Destroyer of the Enemy'.

What is an SSBN?

An SSBN (Ship, Submersible, Ballistic, Nuclear), or nuclear-powered ballistic missile submarine, is a vessel equipped to launch submarine-launched ballistic missiles (SLBMs) armed with nuclear warheads, serving as a crucial component of a nation's nuclear deterrence.

 

INS Arighat is an advanced variant of the INS Arihant, the first boat in the Arihant-class series of indigenous nuclear submarines. It will complement INS Arihant, which has been in service since 2009. The construction of INS Arighat began in 2017 at the Ship Building Centre (SBC) in Visakhapatnam.

The submarine is reportedly capable of achieving a maximum speed of 12–15 knots (22–28 km/h) on the surface and up to 24 knots (44 km/h) while submerged. It features four launch tubes in its hump, allowing it to carry either four nuclear-capable K-4 SLBMs with a range exceeding 3,500 kilometres or twelve K-15 SLBMs with a range of approximately 750 kilometres.

The K-15 missiles can also be fitted with strategic nuclear warheads, and the submarine will be armed with torpedoes as well. Both INS Arihant and INS Arighat are powered by 83 MW pressurised water reactors, allowing them to remain submerged for extended periods. The Arihant class, meaning "Destroyer of the Enemy" in Sanskrit, represents a significant leap in India's underwater capabilities.

SSN vs SSBN submarines

Nuclear attack submarines (SSNs) are primarily designed for anti-submarine warfare, anti-surface ship operations, and intelligence gathering. These vessels are equipped with torpedoes and occasionally cruise missiles, but they do not carry ballistic missiles. Their main focus is on tracking and engaging enemy submarines and surface vessels, as well as providing support for land operations through precision strikes using cruise missiles.

Typically smaller and more agile, SSNs (Ship Submersible Nuclear) are optimised for speed and manoeuvrability. They can be powered either by nuclear reactors or conventional diesel-electric systems, making them versatile and capable of performing a wide range of missions, including reconnaissance and special operations support.

In contrast, SSBNs are larger, designed to carry and launch SLBMs from vertical launch systems. They emphasise stealth and survivability to remain undetected while on patrol, enhancing their deterrence capability.

Future SSN plans

Under Project 75 Alpha, India has outlined plans to construct six SSNs, approved by the Cabinet Committee on Security in February 2015. These submarines are expected to have a displacement of around 6,000 tonnes and will be built at the Shipbuilding Centre in Visakhapatnam. Design work is nearly complete, with the first submarine expected to enter service by around 2032.

The SSN programme will be developed in phases, starting with the first three submarines, followed by an additional three in subsequent phases. Future designs may incorporate advanced technologies, potentially allowing for submarines with a displacement exceeding 8,000 tonnes if required.

Akula-Class lease

Besides indigenous development, India plans to lease another Akula-class submarine, INS Chakra III, from Russia, expected to be delivered by 2025. This will serve as an interim solution while the indigenous SSNs are under development.

India previously operated INS Chakra II, an Akula-class submarine leased from Russia in 2012 for a 10-year period. This submarine was decommissioned in 2021 after the lease expired. India has now signed a $3 billion agreement with Russia to lease another Akula-class submarine, expected to join the Indian Navy by 2025. This new submarine will replace INS Chakra II and is intended to significantly enhance India's underwater capabilities.

The Akula-class submarines are known for their stealth and advanced technology, allowing them to operate undetected for extended periods. They are versatile, capable of hunting enemy submarines and conducting intelligence operations. The induction of another Akula-class submarine is seen as a strategic move to bolster India's naval power and enhance its deterrent capabilities in the Indian Ocean Region (IOR). It will also serve as a valuable training platform for Indian crews, particularly in operating and maintaining nuclear submarines, which is crucial for India's ongoing SSN development under Project 75 Alpha.

How will SSBNs help India?

Located at the heart of the Indo-Pacific, India now has two SSBNs, INS Arihant (S-2) and INS Arighat, providing significant strategic leverage and acting as a deterrent to any navy seeking to assert dominance in the region. These submarines are a critical part of India's nuclear triad and its second-strike capability, reinforcing its no-first-use policy.

India already possesses land-based nuclear missiles, such as the Agni series, and air-launched nuclear capability. The SSBNs are set to become the most potent weapons in India's nuclear triad. The Centre aims to build both nuclear and conventional submarines as part of its long-term submarine acquisition and capability development plan. India plans to develop five Arihant-class boats along with six nuclear attack submarines to be built in three blocks.

India’s third SSBN, INS Aridaman or S4, is also slated for commissioning next year, followed shortly after by a fourth SSBN codenamed S-4, various media outlets reported.