INS Arihant

INS Arihant is India’s first indigenously built nuclear-powered ballistic missile submarine (SSBN), representing a major milestone in the country’s strategic and technological capabilities. It forms the core of India’s nuclear triad, providing the nation with the assured second-strike capability essential for credible nuclear deterrence. As a product of decades of research, engineering, and collaboration under the Advanced Technology Vessel (ATV) Project, INS Arihant marks India’s entry into the elite group of nations possessing nuclear-powered ballistic missile submarines, alongside the United States, Russia, China, the United Kingdom, and France.

Background and Development

The conceptual origins of INS Arihant can be traced to the 1970s, following India’s first nuclear test in 1974. Recognising the importance of a survivable nuclear deterrent, India initiated the Advanced Technology Vessel (ATV) programme in the 1980s. The project aimed to develop a domestically designed and built nuclear-powered submarine capable of carrying strategic ballistic missiles.
The programme was a joint venture involving the Indian Navy, the Defence Research and Development Organisation (DRDO), the Department of Atomic Energy (DAE), and Bharat Heavy Electricals Limited (BHEL), with technical support from Russia. Construction began in the early 2000s at the Ship Building Centre (SBC) in Visakhapatnam, Andhra Pradesh, a high-security naval facility designed specifically for the development of nuclear submarines.

Launch and Commissioning

INS Arihant was launched on 26 July 2009 by then Prime Minister Manmohan Singh, symbolically coinciding with Kargil Vijay Diwas, a day commemorating India’s military success in the 1999 Kargil conflict. After extensive sea trials and reactor tests, it was formally commissioned into the Indian Navy in August 2016 by Prime Minister Narendra Modi.
The name Arihant, meaning “destroyer of enemies,” reflects the submarine’s strategic deterrent role. Its successful induction placed India among the few nations with indigenous nuclear submarine capability, a feat that underscored technological self-reliance in defence manufacturing.

Design and Technical Specifications

INS Arihant’s design is based on a blend of indigenous innovation and Russian submarine technology. The vessel incorporates state-of-the-art systems for propulsion, communication, and weapons control.
Key specifications include:

• Type: Nuclear-powered ballistic missile submarine (SSBN)
• Displacement: Approximately 6,000 tonnes when submerged
• Length: Around 111 metres
• Beam: 11 metres
• Propulsion: One 83 MW pressurised light-water reactor (PWR) fuelled by enriched uranium, developed with assistance from the Bhabha Atomic Research Centre (BARC) and fabricated by BHEL
• Speed: About 12 knots (22 km/h) on the surface and up to 24 knots (44 km/h) when submerged
• Crew: Approximately 90 to 100 personnel, including officers and sailors
• Endurance: Capable of operating underwater for extended durations, limited only by crew endurance and supplies

Armament and Capabilities

The primary armament of INS Arihant consists of submarine-launched ballistic missiles (SLBMs), giving it its strategic nuclear deterrence role.

1. K-15 Sagarika Missiles:
   • Range: Approximately 750 kilometres
   • Payload: Capable of carrying a nuclear warhead
   • Tested successfully multiple times and forms the initial operational missile complement.
2. K-4 Missiles (under development and testing):
   • Range: Around 3,500 kilometres, significantly extending the reach of India’s sea-based deterrent.

The submarine features four vertical missile silos, each capable of carrying multiple K-15 or K-4 missiles, depending on mission configuration. In addition to ballistic missiles, Arihant can also deploy torpedoes for self-defence against enemy submarines and surface vessels.

Strategic Importance

INS Arihant plays a critical role in India’s nuclear triad, which comprises three pillars of nuclear deterrence:

1. Land-based missiles, such as the Agni series;
2. Air-delivered nuclear weapons, through strategic bombers;
3. Sea-based nuclear weapons, deployed on SSBNs like INS Arihant.

The strategic rationale behind sea-based deterrence lies in survivability. Unlike land-based or air-based platforms, a submarine operating underwater is extremely difficult to detect, ensuring that India retains a retaliatory capability even after a potential first strike. This aligns with India’s doctrine of credible minimum deterrence and no-first-use of nuclear weapons.
The operationalisation of INS Arihant thus signifies India’s transition from a regional power to a global nuclear-capable maritime force.

Trials and Operational Milestones

Following its launch, INS Arihant underwent rigorous testing and validation phases, including harbour trials, sea trials, and weapon firing tests. In November 2018, it successfully completed its first deterrence patrol, a 20-day mission confirming its operational readiness. This achievement marked the completion of India’s nuclear triad, as officially announced by the Prime Minister.
The submarine has since been deployed periodically for strategic patrols, maintaining secrecy about its movements and operations, consistent with the operational norms of nuclear deterrence.

Successors and Future Developments

INS Arihant is the lead vessel of the Arihant-class SSBNs. Several follow-on submarines are at various stages of construction and testing to enhance India’s sea-based deterrent:

• INS Arighat: The second SSBN, launched in 2017 and currently undergoing sea trials.
• Additional submarines (code-named S-4 and S-4*), with greater missile-carrying capacity and extended range, are under development.
• A new generation of SSBNs, known as the S-5 class, is planned with larger displacement and advanced reactor technology to increase operational range and endurance.

Symbol of Indigenous Capability

INS Arihant is a testament to India’s indigenous defence and scientific capabilities. The project involved close collaboration between multiple agencies, including the Indian Navy, BARC, DRDO, BHEL, and several private industries. It also marked a significant leap in the mastery of nuclear propulsion, underwater systems integration, and strategic weapons deployment.
The success of the Arihant project has also paved the way for parallel advancements in nuclear-powered attack submarines (SSNs), which will strengthen India’s conventional maritime deterrence capabilities.

Strategic and Geopolitical Implications

The induction of INS Arihant enhances India’s maritime security in the Indian Ocean Region (IOR), a zone of increasing strategic competition. It provides deterrence not only against nuclear threats but also strengthens India’s overall defence posture vis-à-vis regional adversaries. The submarine’s presence serves as a stabilising factor in South Asia by reinforcing the concept of second-strike survivability and deterring potential aggression.
In geopolitical terms, INS Arihant underscores India’s emergence as a responsible nuclear power committed to maintaining peace through credible deterrence. It also contributes to safeguarding India’s extensive maritime interests, including sea lanes of communication, exclusive economic zones, and strategic chokepoints.