Up to now only the club of established nuclear powers had SSBNs, the United States, the Soviet Union/Russia, France, Britain and China, and in the latter two cases that status has been tenuous. Britain's SSBNs have used American-built missiles (first the Polaris, then the Trident), while the actual operability of China's Xia class subs has long been in doubt.
The acquisition of SSBNs in all these cases has had two purposes.
The first is a more robust nuclear deterrent. Bombers are more flexible, while land-based missiles have higher performance and greater accuracy, but submarine-based missiles, because of their mobility and the stealthiness of their platforms, are the hardest for an enemy to target, giving their owners a "second-strike" capability.
It may be particularly significant that the "Advanced Technology Vessel" project apparently began with the intention of producing a nuclear-powered attack boat, and only later sought to produce an SSBN. Three years ago, I argued in The Submarine Review that
submarines are likely to increasingly be used in niche, asymmetrical or supporting roles, in smaller and poorer navies as well as the wealthier ones finding themselves without traditional challengers,rather than the traditional sea denial mission, given their high cost and relative inefficiency in that role.
The second is prestige. From a traditional "realist" perspective, nothing says that a country has arrived as a world-class naval power, a nuclear power and a just plain global power quite like these systems. (Indeed, SSBNs have been justly compared to early twentieth century dreadnoughts by some writers.) This matters because of India's ambitions as a global power (particularly in, but not limited to, the Indian Ocean basin), and because doing nuclear and rocket-type things remains a cheap and easy way for governments to look modern, powerful and important to others, and to their publics-rather than, for instance, delivering quality public services or appreciably raising living standards.
Nonetheless, the launch of the Arihant does not realize those two objects quite so fully as it might seem to at first glance, because
* The sub is a smaller vessel than the other nations mentioned above operate, displacing just 6,000 tons; and while it is carrying a dozen missiles, their performance is comparatively limited. The figure generally given for their range is 750 kilometers. By comparison, the Trident II missile the U.S. uses has a range of over 11,000 kilometers, and that with a considerably larger payload. In short, the Arihant carries fewer missiles with a much shorter reach and a lower overall punch (though in all fairness, comparisons of megatonnage and throw-weight do get absurdly theoretical in a hurry).
* India's construction of the sub was not only belated (the program began in the 1970s), but dependent on Russian support, the full details of which have not been clarified, but one important aspect of which is that the training of the Arihant's crew will actually take place on a rented Russian submarine, the INS Chakra, a Russian Akula II. (This is not the first Chakra, India having operated one from 1988 to 1991, also a rented Soviet sub, a Charlie class SSGN.)
Simply put, it is not necessarily an example of successful indigenization, even calling to mind the country's experience with the Arjun tank-which arrived late, overbudget, heavily dependent on German design and German components (half the Arjun's components were actually Germany-made, according to a report from a few years ago), and left the Indian army still dependent on imports (Russian tanks likely to remain prominent in its armory in the future, as Russian-and German-subs will remain in its navy).
* The Arihant is not a commissioned, in-service vessel, but currently on sea trials, an actual operational vessel "still three years away" (c. 2012)--and even that would represent a tenuous dimension of its arsenal. Other navies generally need several boats to keep one continually on station, as a really credible second-strike capability (such as that enjoyed by Britain and France) generally calls for, and that goal is even more distant.
In short, what India has is an untested vessel that is not only of modest performance in comparison with its American, Russian, French and British equivalents, but still a long way from giving it the really operational "second-strike" capability sought after, and even that was achieved with what may have been a very high level of foreign assistance.
This is not terribly surprising, in light of the constraints on Indian economic and industrial capabilities, despite the popular image of a booming, rising India. India's GDP at official exchange rates is still just $1.2 trillion, or about $1,050 per head. Counting in Purchasing Power Parity, the result is a more impressive $3.2 trillion, or $2,800 per capita--but this still leaves it ranking just 168th in the world according to the CIA World Factbook.
Looked at another way, India is a country where sixty percent of the population is still working in agriculture.
Simply put, an SSBN program (certainly one comparable to that long taken for granted by the permanent members of the UN Security Council) on this base is a matter of overreaching, all the more unfortunate given that there are any number of worthier and more pressing projects toward which the money could have been put.