In November, India’s only operational nuclear-powered and nuclear-armed submarine, INS Arihant, completed its first deterrence patrol.

This development signalled the operationalisation of the triad – that is, the capability to launch a nuclear weapon from land, air and water.

However, there are several reasons why INS Arihant does not really give India a credible nuclear deterrent at sea.

One, the success of the deterrence patrol suggests India has overcome some of the command and control challenges of maintaining a submarine nuclear force.

But, among other things, the fact that the Chairman Chiefs of Staff Committee, a key part of the nuclear command chain, serves on a part-time basis while also discharging its duty as the head of one of the three services is problematic and needs urgent reform.

Two, the 750-km range of the K-15, which arms the boat, is far below what is required. When patrolling in the Bay of Bengal, INS Arihant can’t strike population and industrial centres in China and Pakistan, which are at least 2,000 kilometres from the northern-most and western-most edges of the water body, respectively.

The next missile in the series – K-4 – provides a solution. But the missile, which reportedly has a range of 3,500 km, is currently under development and a test is scheduled for January 2019.

And three, India remains far from matching China’s capabilities, both in terms of numbers and experience. Beijing currently has four SSBNs or ballistic missile submarines and India is likely to reach the same number, by the most optimistic accounts, only by the end of the next decade.

So, it’s safe to say, INS Arihant’s successful deterrence patrol is only the first step in what promises to be a long and onerous process for India in maintaining a credible deterrent at sea.

Till then, India still has critical gaps to fill in the sea leg of its nuclear triad.