The subsurface dimension is a vital element in any nation’s maritime security and the lack of credible subsurface capability is critical for national security. In the contemporary global security context where the spectrum of conflict has widened from the strategic at the higher end to low intensity conflict by non-state actors at the lower end, subsurface capability includes a range of options from strategic ballistic missile submarines on one end to swimmer delivery vehicles, diver detection sonars and even underwater nets and booms near ships in harbour on the other. However, submarines are the most potent and most visible instruments in a nation’s subsurface and indeed overall naval capability.

In the last 100 years or so, subsurface technology and submarine warfare has come a long way from the days when a British Admiral called it “underhand, unfair and damned un-english” and wanted to “treat all submariners as pirates…and hang all crews”. In fact, it is perhaps the submarine more than any other military platform that has influenced the outcome of all major conflicts of the 20th century. The indications so far in this millennium show no signs of this influence diminishing.

Historical Perspective

Submarines played an important role in the First World War though the limitations of technology considerably restricted their undersea combat capability. Submarines were used in the Second World War and German U-boats became a legend. They were perhaps the single most effective weapon platform which shaped the course of the war.

The Cold War which ‘raged’ for over four decades by the cat and mouse games played out beneath the waves by the nuclear submarines of the two major protagonists. Armed with enough firepower to annihilate the entire world several times over, nuclear powered ballistic missile submarines (SSBN) became not only the most potent element of the nuclear triad but also the most preferred platform for an effective second strike capability. However, the end of the cold war notwithstanding, the relevance of submarines as the ultimate weapon of deterrence did not diminish.

The cataclysmic events of 9/11 heralded the arrival of the new millennium in a dramatic fashion. The ‘global war on terror’ that followed led to a paradigm shift in the global and regional security calculus in the post-Cold War era. Naval operations, and in particular anti-submarine warfare, which had appeared to be losing relevance in the immediate post-Cold War period, suddenly found pitch forked back into the limelight although in a somewhat different context. From the open ocean cold war scenario, the focus shifted to the littoral. Shallow water anti-submarine warfare (ASW) began to get the attention of the military planner. Conventional submarines, traditionally smaller and quieter and with operational limitations compared to their nuclear counterparts also regained prominence. Countries such as the US, UK and France which had done away with diesel submarines (Admiral Hyman Rickover considered the father of nuclear submarines, had contemptuously dismissed these as submersibles) realised the importance of conventional submarines in restricted and shallow water operations. They sought to regain the diminishing art (or science) of ASW by seeking to exercise with navies that operated conventional submarines.

At present, there are more than 40 navies operating submarines. Of these, the big five at the top table of the UN have a nuclear submarine based deterrence capability. India is on the cusp of operationalising this capability. Submarines, nuclear or conventional, are expensive to build and equally expensive to maintain. Therefore, only those countries, with a security imperative necessitating the sizeable investment essential, develop a credible submarine capability. The fact that more than 40 choose to do so underlines their importance. In the last decade or so, there has been proliferation of submarines in the Indian Ocean/Asia Pacific Region as there is no doubt that this region is going to be the focus of the world in the 21st century. Even countries without the wherewithal to operate submarines are considering cheaper though effective alternatives for a limited subsurface capability by deploying midget submarines, swimmer delivery vehicles, remotely-operated vehicles, unmanned underwater vehicles, sonars and surveillance devices, etc.

There are various types of submarines designed to address a specific or a range of specific threats. Advancement in technology has ensured that the sea-based leg of the triad is the most effective. The ability of SSBNs to travel several hundred kilometres in a day and their unlimited endurance gives them the advantage of mobility, stealth and surprise while making them relatively invulnerable to retaliatory attack. Coupled with their power projection capability, are the preferred instrument of strategic deterrence. The UK’s justification to develop their next class of SSBN is based on this argument.

The belief that with the end of the Cold War, the importance of the SSBN would diminish has largely been laid to rest as the world becomes an increasingly dangerous place to live in. While the numbers have reduced (though still sufficient to destroy the world), their relevance has increased. This is borne out by the fact that despite the drastic cuts in defence spending in the post-Cold War era and further pruned by the global financial downturn, all the big five powers are continuing with their strategic submarine programmes—all five are in various stages of planning the replacement of their current SSBNs.

The undersea brinkmanship during the Cold War which exemplified the Cold War itself, brought to the fore, the nuclear powered attack submarine also called the SSN. Smaller than the SSBN, and therefore faster, quieter and more agile, these submarines were deployed to shadow the SSBNs of the enemy. Declassified accounts of incidents between the US and Soviet submarines are now making their way into print and some of these are even more hair raising than the ‘romanticised’ techno thrillers by authors like Tom Clancy, Larry Bond and Patrick Robinson. The SSN is perhaps the most potent platform in the maritime battlespace. In the current conflict scenario with littoral warfare being the buzzword and support of land forces being a major naval role, SSNs have more than proved their worth with the ability to launch precision land-attack missiles from distant ranges and thus pulverising the enemy even before the land assault begins. The successful bombardment of Afghanistan by the Tomahawk land-attack missile fired by US SSNs prior to the land forces initiative in Afghanistan is a case in point. Robust SSN programmes are under way in all the major navies.

Conventional submarines, or SSKs as they are known, remain the preferred choice of most navies either due to security imperatives, cost or technology absorption capability. Notwithstanding the fact that submarines are expensive to operate, their inherent advantages of lethal firepower, stealth and mobility in restricted and shallow waters, enables them to punch far above their weight against heavyweight adversaries. They are the preferred choice for ‘sea denial’ or denying the enemy the use of the sea vis-a-vis sea control which is the endeavour of larger navies against a weaker adversary. Modern technology has effectively addressed their inherent limitations of limited endurance, limited speed and the consequent lack of ability to manoeuvre to engage the enemy within the range of its weapons. Modern technology has effectively addressed these limitations. The advent of air independent propulsion and the tube launched missile has greatly enhanced their operational effectiveness in the littoral. The importance of conventional submarines in a nation’s maritime and military equation can never be underestimated which is evident in the number of recent entrants to the club of submarine operating navies.