The K-4, developed by India’s Defence Research and Development Organisation (DRDO) with a range capability of 3,500 km, will be an intermediate range submarine launched ballistic missile (SLBM).

The K-4 arms India’s first indigenously-Ship Submersible Ballistic Nuclear (SSBN) the INS Arihant class submarines, completing India’s nuclear triad of delivery vehicles.

DRDO in April 2019 had test-fired the K-4 nuclear-capable submarine-launched ballistic missile (SLBM)–from aboard the INS Arihant, the first submarine in its class. According to press reports, the test was “highly successful & a roaring success” and involved a fully operationally configured K-4 with a dummy payload. Notably, the K-4 was tested using depressed trajectories.

The K-4 aboard the INS Arihant and future Indian SSBN’s will give India the ability to target most of China, including Beijing, and all of Pakistan when operating in the northern parts of the Bay of Bengal.

While technical details are hard to ascertain given the levels of secrecy involved, the K-4, which underwent its last test on 19th Jan 2020, reportedly has a length of 12 metres, a diameter of 0.8 metres, and can carry a conventional/nuclear payload of up to 2 tons.

The missile is powered by solid rocket boosters and is highly accurate with a near-zero circular error probability.

The INS Arihant will have the capability to carry four K-4 missiles, and the follow-on SSBN’s that are planned will have the capacity to carry eight K-4 or such SLBM’s each. Future submarines will reportedly be larger and will carry missiles of longer range like the S-5, which will have a reach of over 5,000 kilometres.

India has an officially adopted posture of no first use and assured retaliation.

Hence, India considered it essential to develop capabilities to eventually deploy continuous at-sea nuclear deterrence to ensure the survivability of its nuclear second-strike capability. DRDO officials in the past have stated that the circular error probable (CEP) of the K-4 to be 40 meters or less, which would make it an ideal weapon system for a sea-based counter-force capability from stand-off ranges.

In theory, a sea-based nuclear deterrent is invulnerable once undersea because it can hide and is not trackable or targetable by adversaries, unlike ground-based systems. This is especially important to India, as its land-based systems will have little reaction time given the proximity of Pakistani and Chinese nuclear weapons.

Pakistan Purchasing Yuan-Class Diesel-Electric Submarines

Pakistan has over the last few years pursued strategic parity with India’s growing underwater nuclear capabilities in an attempt to negate its conventional superiority.

The Pakistani navy created a strategic command a few years ago which went on to recently test a nuclear capable submarine launched cruise missile with a range of 450 kilometres in the form of the  unverifiable existence (mythical) of Babur-III.

Islamabad has claimed second-strike capability. Pakistan is currently in the process of purchasing eight Yuan-class diesel-electric submarines from Beijing. Added to the existing three French Agosta-90B/Khalid and two Agosta-70 submarines of the Pakistan Navy and the ambiguity of deploying nuclear-armed cruise missiles on conventional submarines will be highly destabilising, with covert help from China.

This would make prosecution of targets vis-à-vis Pakistan extremely difficult for the Indian Navy in the years to come.

China’s Nukes Can Destroy Most of India

China, on the other hand, has an operationalised at-sea nuclear deterrent and had sent a Jin-class SSBN out on its first deterrent patrol, according to press reports, in December 2015.

The submarine is armed with up to 12 JL-2 nuclear armed SLNM’s with a estimated range of 7,200 kilometres, meaning most of India falls within its range from its operating bastion of the South China Sea.

India’s eventual induction of SSBN’s in numbers armed with K-4 missiles is unlikely to change or draw any reaction from Beijing apart from an increase of probes by the Chinese Navy in the Bay of Bengal region to track and monitor patterns in India’s SSBN deployments.

From Civilian Control of Weapons To Military Control

India is a nuclear weapons state, the newly appointed CDS will also act as the military adviser to the Prime Minister on nuclear issues. There are certain formalities such as the charter, hierarchy in the government and the duties of the CDS which has been chalked out. The primary responsibility of the CDS would be to coordinate and prioritise procurement for the military based on the inputs from the three service chiefs and the secondary more importantly will have nuclear weapons under his charge.

Historically, Indian nuclear warheads and delivery systems are unmated and housed at different locations. In stark contrast and as a first, deployment of an undersea launch capability will require weaponisation of the K-4 and represents a shift from civilian control of nuclear weapons to military control.

The induction in the future of the K-4 will require a review and strengthening of India’s C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance) capabilities and procedures to prevent any unauthorised commands or accidental launches. With the induction and deployment of the K-4 in the coming years, India will field a comprehensive spectrum of options which fulfil India's deterrence and strategic needs. (With inputs from ORF)