The construction of the advanced technology vessel (ATV), as the project is designated, is in line with India's nuclear doctrine enunciated in 1999 that calls for its nuclear forces to be effective, enduring, diverse, flexible, and responsive to the requirements in accordance with the concept of credible minimum deterrence. The doctrine calls for high survivability against surprise attacks and for rapid punitive response.

A nuclear submarine, which can remain submerged for prolonged periods of time and is virtually undetectable underwater, therefore, meets all these criteria and offers an invaluable launch platform for nuclear weapons, the doctrine says.

It is the world's most powerful deterrent force -- a stealthy undersea platform with enormous nuclear firepower. For a country like India with a no-first use policy, it is vital because it prevents a potential adversary from launching a crippling first-strike to knock out all nuclear weapons, the doctrine says.

The Indian Navy will also get a Russian-built Akula class nuclear submarine, to be commissioned as INS Chakra, by the year-end. Currently undergoing sea-trials, the delivery date for the Russian submarine was pushed back following an accident on board. The navy will use the submarine to train its crew in handling nuclear-powered vessels.