​In pics: India’s sea-based deterrent triad – INS Arihant, Arighaat & Aridhaman

The INS Arihant (Hull Number S2) holds a historic position as India’s first indigenously built nuclear-powered ballistic missile submarine (SSBN) and the lead ship of its namesake class. Serving as a primary strategic nuclear deterrent platform, it completes India’s Nuclear Triad by providing the essential sea-based leg of land, air, and water-borne deterrence. Operating under the Eastern Naval Command, the vessel is specifically designed to offer a survivable second-strike capability, ensuring that India maintains a credible defense posture.

The INS Arihant is equipped with a versatile offensive suite designed for both long-range strategic strikes and tactical maritime defense. Its primary strategic armament consists of four Vertical Launch System (VLS) tubes, which can be configured to carry either 12 K-15 (Sagarika) submarine-launched ballistic missiles (SLBMs) with a range of approximately 750 km, or four K-4 SLBMs with a more extensive range of 3,500 km. For tactical engagements, the submarine features six 533 mm torpedo tubes, providing the capability to fire heavyweight torpedoes and potentially anti-ship missiles, ensuring its effectiveness against surface and underwater threats.

INS Arihant was developed under the Advanced Technology Vessel (ATV) Project and constructed at the Shipbuilding Centre (SBC) in Visakhapatnam. Its reactor was developed by BARC in collaboration with DRDO and the Navy. The submarine was laid down in 2004 and launched on July 26, 2009. It achieved reactor criticality in 2013, followed by sea trials between 2014 and 2016. INS Arihant was commissioned in August 2016 and completed its first deterrence patrol in 2018, marking a significant milestone in India’s indigenous nuclear submarine programme.

INS Arihant is powered by an 83 MW pressurised light water reactor (CLWR) fuelled by enriched uranium. The submarine operates on a single shaft driven by a steam turbine. It can achieve an approximate speed of 24 knots while submerged and between 12 and 15 knots when surfaced. The vessel has an estimated diving depth exceeding 300 metres, enabling it to operate effectively in deep-sea environments.

The INS Arihant plays a pivotal role in India's national security by establishing a credible sea-based nuclear deterrent and ensuring a guaranteed second-strike capability in the event of a nuclear attack. Operating primarily within the Indian Ocean Region, the vessel is designed to provide a highly survivable and concealed nuclear launch platform.​

The INS Arihant is a formidable vessel with a length of approximately 111.6 meters, a beam of 11 meters, and a draft of 9.5 meters. It features a robust double-hulled structure specifically engineered to enhance survivability during high-stakes underwater operations. When surfaced, the submarine has a displacement of roughly 6,000 tonnes. Due to its advanced nuclear propulsion, the Arihant possesses a virtually unlimited operational range; its patrol endurance is not restricted by fuel, but rather by the limit of crew supplies and provisions on board.

The INS Aridhaman represents a significant step forward in naval engineering, characterized by its impressive scale and advanced structural design. Measuring slightly longer than the 111.6m class baseline with an estimated beam of 11–12 meters, this vessel is built with a double-hull configuration to maximize survivability during high-stakes operations. Its massive displacement of 6,500–7,000 tonnes is a deliberate design choice, providing the necessary volume to house sophisticated onboard systems and an expanded missile payload. Powered by nuclear propulsion, the Aridhaman boasts a "virtually unlimited" operational range.

The INS Aridhaman is a product of India’s ambitious Advanced Technology Vessel (ATV) Project, constructed at the Shipbuilding Centre (SBC) in Visakhapatnam. A critical component of its design is the nuclear reactor, which was developed through a high-level collaboration between BARC, DRDO, and the Indian Navy. While much of the project remains classified, key milestones indicate that the construction phase spanned the 2010s, with significant progress reported by 2019. Currently, the vessel is in the ongoing or advanced stages of sea trials according to open-source reporting, with formal commissioning expected to follow their successful completion. Building on the foundation of its predecessors, the Aridhaman incorporates incremental technological refinements over both the INS Arihant and INS Arighaat, solidifying its role as a more advanced successor in the fleet.

INS Aridhaman’s strategic armament includes eight expected vertical launch system (VLS) tubes capable of deploying K-15 (Sagarika) submarine-launched ballistic missiles (SLBMs) with a range of approximately 750 km, as well as K-4 SLBMs with a range of around 3,500 km. The submarine may also be equipped with longer-range missiles in the future, further increasing its strategic reach. Additionally, it carries six 533 mm torpedo tubes capable of launching heavyweight torpedoes for self-defense.

The INS Aridhaman has a crew strength of over 100 specialized personnel, including nuclear engineers and submarine warfare operators. These experts are trained to conduct long-duration patrols while maintaining high levels of stealth and operational readiness. INS Aridhaman is intended to perform extended deterrence missions quietly, remaining undetected while ensuring strategic stability.

INS Aridhaman, India’s upcoming nuclear-powered ballistic missile submarine, is designed to significantly strengthen the country’s sea-based deterrence capabilities. The submarine is powered by an upgraded Pressurised Light Water Reactor (CLWR) with an estimated power output of over 80 MW, enabling extended underwater operations without the need for refuelling. Its propulsion system uses a steam turbine with a single shaft, allowing the vessel to reach an estimated submerged speed of around 24 knots. With a projected diving depth of more than 300 metres, the submarine is built for deep and stealthy patrols.

​The submarine is powered by an upgraded pressurized light water reactor (CLWR) generating over 80 MW of power. This drives a single-shaft steam turbine propulsion system, allowing the vessel to achieve an estimated submerged speed of approximately 24 knots. INS Aridhaman is designed to operate at diving depths beyond 300 meters, providing both stealth and survivability in strategic patrols.​

​The INS Arighaat serves as a critical component of India’s naval defense, featuring a versatile array of weapons and combat systems. Its strategic armament is centered around four Vertical Launch System (VLS) tubes, which can be configured to carry either 12 K-15 (Sagarika) submarine-launched ballistic missiles (SLBMs) with a range of approximately 750 km, or four K-4 SLBMs that extend its reach to roughly 3,500 km.

The INS Arighaat is powered by a sophisticated Pressurised Light Water Reactor (CLWR) in the estimated 80+ MW class, which utilizes a single-shaft steam turbine for its primary propulsion. This advanced nuclear power plant allows the submarine to achieve an approximate submerged speed of 24 knots, while its surfaced speed is estimated between 12–15 knots. Engineered for deep-sea operations, the vessel has an estimated diving depth of 300+ meters. Crucially, this nuclear propulsion system enables the Arighaat to conduct prolonged submerged operations for extended periods without surfacing.

The INS Arighaat serves as a cornerstone of India’s Advanced Technology Vessel (ATV) Project, marking a significant leap in indigenous naval engineering. Constructed at the Shipbuilding Centre (SBC) in Visakhapatnam, the vessel features a nuclear reactor developed through a high-level collaboration between BARC, DRDO, and the Indian Navy. The submarine's developmental journey spanned over a decade: it was laid down in 2011, launched on November 19, 2017, and underwent extensive harbour and sea trials between 2018 and 2024. Officially commissioned on August 29, 2024, INS Arighaat is an evolved and refined successor to the INS Arihant, incorporating several incremental design and system improvements to bolster the nation's maritime strength.

The INS Arighaat is the second indigenously built Arihant-class nuclear-powered ballistic missile submarine (SSBN), carrying the hull number S3. As a critical component of India’s Nuclear Triad, this vessel serves as a strategic nuclear deterrence platform designed to strengthen and sustain continuous sea-based deterrence patrols. Officially commissioned on August 29, 2024, the INS Arighaat is stationed under the Eastern Naval Command.

INS Arighaat is approximately 111.6 metres long, with a beam of around 11 metres and a draft of roughly 9.5 metres. Built with a double-hulled structure, the submarine is designed to enhance survivability and underwater resilience. It has a displacement of about 6,000 tonnes based on the class baseline, with marginal refinements reported. Powered by nuclear propulsion, INS Arighaat has a virtually unlimited operational range, allowing it to undertake prolonged patrols without the need for frequent refuelling.

INS Arighaat expands India’s sea-based nuclear deterrent and enables rotational deterrence patrols to ensure sustained coverage. Its induction enhances the survivability of India’s nuclear arsenal and strengthens deterrence posture in the Indian Ocean Region. With multiple SSBNs operational, India moves closer to maintaining a continuous at-sea deterrence capability. The submarine has a crew strength of approximately 95 to 100 personnel, including specialised nuclear engineers and submarine warfare experts, and operates under the Eastern Naval Command.