Following a successful second test of India's Nirbhay cruise missile on October 17, 2014 it is a good time to discuss the Nirbhay's role. This second test follows the first test on March 12, 2013. Being a relatively small missile the Nirbhay (Sanskrit for "fearless") can potentially be launched by any means including land-mobile launchers, fighter-bombers, surface ships or (nuclear or conventionally propelled) submarines. The Nirbhay's warhead may be conventional high explosive, nuclear or chemical (biological is possible but increasingly unlikely). The inherent vulnerability of this subsonic cruise missile to anti-aircraft or dedicated anti-missile defences makes it less suitable as a nuclear delivery vehicle only. The dual-use or triple-use ambiguity makes it inadvisable to fire a Nirbhay as a first strike against a nuclear armed country.
The Nirbhay might fit well into India's second strike only strategy against the most likely aggressors (Pakistan and China). The Nirbhay's estimated range of 1,500 km would permit any part of Pakistan to be hit from Indian territory or perhaps from the Arabian Sea. From the Bay of Bengal some Chinese targets could be hit. With difficulty Nirbhay armed Indian subs could cross into the Western Pacific in order to hit some of China's major coastal cities. If fired by submarine the Nirbhay's 0.52m diameter makes it deliverable from a conventionally powered submarine's (SSK's) standard 0.533m torpedo tubes - thus giving SSKs a more potent nuclear warfare role than shorter range nuclear tipped Klub or Harpoon SLCMs allow.
Alternatively Nirbhays could be fired from a future Indian SSN's or SSGN's vertical launch tubes - thus eventually giving India a dual-use capability for those two submarine classes. In the Indian Ocean most of India's potential targets will be non-nuclear armed countries making these dual-use subs more economical than nuclear weapon only K-15 or K-4 armed future Indian SSBNs.
Further details on the second test and comments on the Nirbhay's strategic role are at http://thediplomat.com/2014/10/meet-indias-new-nuclear-cruise-missile/ .