A FEW weeks ago, a ceremony took place in Visakhapatnam, India, that passed largely unnoticed. The ceremony marked the formal induction into the Indian Navy of INS Aridhaman, the country’s third nuclear-armed submarine. Pakistan offered no public response, but what slipped beneath the waves that morning would shape South Asia’s security landscape for decades to come.

Land-based missiles can, in theory, be located and destroyed before launch. Aircraft carrying nuclear weapons can be intercepted. A nuclear-armed sub-marine, however, presents a funda-mentally different challenge. Hidden and difficult to neutralise, it preserves the ability to retaliate even after a first strike. This is what strategists call the second-strike capability: the assured ability to respond after absorbing an attack. In deterrence theory, it is considered the ultimate stabiliser. If both sides know that retaliation is inevitable, the incentive to strike first is significantly reduced. A credible second strike does not merely penalise aggression; it makes aggression strategically irrational.

India has been moving steadily towards this capability for years. INS Aridhaman is the third submarine of its class, while a fourth is undergoing sea trials and is expected to enter service around 2027. A fleet of four submarines would allow India to maintain a continuous at-sea nuclear presence, with vessels rotating between active patrol, preparation for deployment, return, and refit. The deterrent would remain permanently operational.

These submarines are reportedly equipped with missiles capable of travel-ling roughly 3,500km, enabling them to target deep inland positions from secure areas within the Indian Ocean. This is much more than a technical improvement; it is a strategic transformation. India no longer needs to deploy submarines close to Pakistani waters.

The interpretation portraying India’s submarine programme primarily as a response to China overlooks a more immediate reality. It is the Pakistan-India rivalry, geographically compressed and prone to crisis, that gives India’s sea-based deterrent its operational urgency.

In South Asia, missile flight times are measured in minutes, and no state can assume its land-based nuclear forces would survive a pre-emptive strike. Nuclear submarines solve that problem by ensuring a survivable retaliatory capability under all circumstances.

For Pakistan, this development presents challenges that are neither temporary nor easily manageable. The first is strategic. Any doctrine contemplating the pre-emptive neutralisation of India’s nuclear forces becomes far less credible once a survivable sea-based deterrent is in place. The second is environmental. The Arabian Sea is no longer solely a conventional theatre; it is increasingly a space for nuclear signalling.

During any future crisis, Pakistani decision-makers will face uncertainties that scarcely existed a decade ago, including questions about the submarine’s location, its orders, and how its movements should be interpreted. The third challenge is asymmetry. Pakistan possesses a limited sea-based nuclear capability, but there remains a substantial structural difference between a limited sea-based option and the continuous underwater nuclear patrol India is now approaching.

Pakistan should resist the temptation to mirror India’s programme directly. A more sustainable response would be to strengthen maritime domain awareness to monitor submarine activity in critical waters. It should maintain a credible, but proportionate sea-based deterrence.

The Indian submarine power demands a reckoning, and the sooner it happens, the better prepared Pakistan will be for the tricky decades that lie ahead of us.

Lt-Col (retd) Syed Raziuddin
Rawalpindi

Published in Dawn, June 15th, 2026