K-15 'Sagarika or 'Oceanic' undergoing qualification test from Nuke Submarine INS Arihant

India’s second nuclear-powered ballistic missile submarine, the INS Arighat, was commissioned into service at Visakhapatnam in the presence of Defence Minister Rajnath Singh on Thursday (August 29, 2024). It joins the first such submarine, the INS Arihant, which was commissioned into service in 2016.

The technological advancements undertaken indigenously on this submarine make it significantly more advanced than its predecessor Arihant, the Defence Ministry said in a statement. The presence of both INS Arihant and INS Arighat will enhance India’s capability to deter potential adversaries and safeguard its national interests, it added.

The K-4 submarine-launched ballistic missile (SLBM) plays a crucial role in enhancing India's nuclear deterrence capabilities. Developed by the Defence Research and Development Organisation (DRDO), the K-4 has a range of approximately 3,500 kilometers, allowing it to target significant areas within adversarial nations, including parts of southern China and Pakistan.

The construction of INS Arighat involved the use of advanced design and manufacturing technology, detailed research and development, the use of special materials, complex engineering, and highly skilled workmanship, the Ministry statement said. “It has the distinction of having the indigenous systems and equipment which were conceptualised, designed, manufactured and integrated by Indian scientists, industry and Naval personnel,” it said.

The completion of the nuclear triad was announced in November 2018, when Prime Minister Narendra Modi announced on social media that INS Arihant had returned from its first deterrence patrol. The advanced technology project began in the 1980s and its first product, the Arihant vessel, was launched in 2009, and eventually commissioned in 2016.

The third of these submarines, which is at an advanced stage of construction, is set to be larger and more capable than the current two submarines in the same class.

K-15 SLBM

INS Arihant carried out a successful launch of a Submarine Launched Ballistic Missile (SLBM) on October 14, 2022. The missile was tested to a predetermined range and impacted the target area in the Bay of Bengal with very high accuracy. All operational and technological parameters of the weapon system have been validated according to a statement issued by the MoD.

Although the ministry did not make an official statement on which missile it fired, sources in the defence establishment indicated it was the 750-km range K-15, which is already in service.

"The successful user training launch of the SLBM by INS Arihant is significant to prove crew competency and validate the SSBN program, a key element of India’s nuclear deterrence capability. A robust, survivable and assured retaliatory capability is in keeping with India’s policy to have ‘Credible Minimum Deterrence‘ that underpins its ‘No First Use’ commitment," the MoD report further added.

The K-4 SLBM For India's Deterrence

The K-4 SLBM is integral to India's second-strike capability, which is a cornerstone of its nuclear doctrine. This capability ensures that India can respond effectively to a nuclear attack, thereby deterring potential aggressors. The K-4's deployment on the INS Arihant, India's first indigenous nuclear submarine, enhances the survivability of India's nuclear arsenal, as submarines can operate undetected underwater.

The K-4 is designed to be deployed from India's Arihant-class submarines, which are part of the country's nuclear triad. Each Arihant-class submarine can carry four K-4 missiles, while future submarines are expected to accommodate up to eight K-4s. This integration not only boosts the strike capacity of the Indian Navy but also enhances the survivability of India's nuclear arsenal by allowing launches from underwater, reducing the likelihood of detection.

India's nuclear strategy is based on the principle of credible minimum deterrence, which aims to maintain a sufficient nuclear arsenal to deter adversaries while adhering to a no first use policy. The K-4 SLBM contributes to this strategy by providing a reliable and potent means of retaliation.

The K-4 can be launched from submarines, which are inherently more difficult to detect and target compared to land-based missile systems. This stealth capability significantly enhances India's deterrent posture, as it complicates the adversary's ability to pre-emptively strike.

The deployment of the K-4 represents a strategic shift from civilian to military control over nuclear capabilities. This transition is significant as it enhances the operational readiness and responsiveness of India's nuclear forces, allowing for a more robust and immediate deterrent posture.

Technological Significance of The K-4 SLBM

The K-4 submarine-launched ballistic missile (SLBM) represents a significant technological advancement for India’s defence capabilities. Here are the key aspects that highlight its importance:

The K-4 has achieved a remarkable reduction in size compared to its predecessor, the Agni-III. While the Agni-III measures 17 meters, the K-4 has been compacted to 12 meters. This reduction is crucial for fitting the missile into the limited hull space of submarines like the INS Arihant-class boats, enhancing the operational viability of India's underwater nuclear deterrent.

The K-4 is powered by a solid rocket propellant and features a sophisticated propulsion system developed by DRDO. This includes three motors responsible for its propulsion, which are designed to ensure high accuracy and reliability during launch.

The missile is engineered to achieve high accuracy, which is vital for effective deterrence. Additionally, it incorporates advanced countermeasures against ballistic missile defence systems, allowing it to evade interception and ensuring that it can successfully deliver its payload to the designated target with deadly accuracy.

Summary

The K-4 (and the K-5) is part of a broader family of missiles, with future submarines expected to carry even more advanced systems, such as the K-5, which will have an extended range. This ongoing development reflects India's commitment to maintaining a robust and modern nuclear deterrent.

INS Arihant is presently armed with a 750 km range K-15 SLBM while a 3,500 km range SLBM K-4 is under development, having been tested for the first time in 2020. The K-4 will become the mainstay of India’s undersea nuclear deterrence, as it gives the stand-off capability to launch nuclear weapons while submerged in Indian waters.

India is also working on a nearly 5,000-kilometre range missile called the K-5.

A robust, survivable and assured retaliatory capability is in line with India’s policy to have a credible minimum deterrence capacity to underpin its ‘no first use’ commitment. In 1998, India conducted nuclear tests under Pokhran-II and in 2003, India declared its nuclear doctrine, even while reserving the right of massive retaliation if it is struck with nuclear weapons.

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