India has launched its first nuclear-powered submarine - becoming only the sixth country in the world to do so.
The 6,000 tonne Arihant was launched by Prime Minister Manmohan Singh, who said said India had no aggressive designs on anyone.
But, he added, the sea was becoming increasingly relevant to India's security concerns.
The BBC reports the Arihant was built entirely in India with Russian assistance. A second is due to be constructed shortly.
It will undergo trials over the next few years before being deployed and will be able to launch missiles at targets 700km away.
The Arihant will carry a crew of 100 and will be able to stay under water for long periods.
Until now, India's submarine fleet comprised conventional diesel-powered vessels.
Only the United States, Russia, France, Britain and China previously had the capability to build nuclear submarines.