A CGI rendering of INS Arihant firing a Sagarika SLBM

The Arihant's first deterrent patrol is commendable, but to get a robust nuclear triad, we'll need more full-range platforms

by Sandeep Unnithan

New Delhi: India recently took its first steps towards establishing the third leg of a nuclear triad: the ability to launch nuclear weapons from under the sea. On November 5, Prime Minister Narendra Modi announced that India's first indigenous ballistic missile submarine (SSBN), the INS Arihant, had completed its first deterrent patrol.

A strategic deterrent patrol is one where an SSBN with a full complement of nuclear-tipped missiles sails towards its intended area of deployment and within range of an adversary's targets. In case of an attack by a nuclear-armed adversary, India's Nuclear Command Authority (NCA) can order the submarine to launch its weapons.

The prime minister's statement assumes significance because it also hints at having established a command chain- the NCA's ability to communicate with a submarine lurking in the depth of the ocean. In the Arihant's case, the order will be passed via a sophisticated Extremely Low Frequency (ELF) communication system near Tirunelvelli in Tamil Nadu.

The Arihant returned to its base in Visakhapatnam on November 4 after a 20-day submerged patrol. The patrol area is a closely guarded secret, but the PM's statement warning of a "fitting response to those who indulge in nuclear blackmail" seems to suggest that the North Arabian Sea, off Pakistan, rather than the East China Sea, was the Arihant's patrol area. (It will take the submarine nearly a month to make the passage to and from China's shores). Deterrent patrols are meant to dissuade a potential nuclear-armed adversary from launching a nuclear first strike. Once a submarine sails out into the deep ocean, it is extremely difficult to detect, track and destroy, making it the most survivable platform of the nuclear triad that consists of aircraft-dropped and ground-fired nuclear missiles.

All five permanent members of the UN Security Council deploy their SSBNs on deterrent patrols. The robustness of the deterrent is decided by missile ranges, number of weapons and, most critically, the ability to have one platform on continuous patrol. China was the last entrant into this club with its SSBN making its first deterrent patrol as recently as December 2015.

India, however, is still years away from a robust third leg. "The triad becomes effective when you have a submarine operational at all times, [and that would require a fleet of four such vessels at the very least]. In our case, a triad is operational only when the Arihant sails," says strategic analyst Bharat Karnad. The 6,000-tonne INS Arihant was inducted into service in August 2016 and is currently armed with 12 B-05/ K-15 SLBMs (submarine launched ballistic missiles), which have a range of 750 km. Its arsenal of four K-4 SLBMs, with a range of 3,500 km, is yet to pass trials.

Three other SSBNs are being built under the Defence Research and Development Organisation's Advanced Technology Vessel (ATV) project in Vizag. A second SSBN, the Arighat, launched last November, is expected to join the navy in a few years. Two more SSBNs are likely to join within the decade. More submarines with longer-ranged missiles means more deterrent patrols and, hence, a credible third leg. The Arihant's first deterrent patrol, though a commendable achievement, should be seen as the first steps in that direction.