NEW DELHI: India on Sunday launched the first nuclear-powered submarine built on its soil, joining just five other countries that can design and construct such vessels, the prime minister's office announced.

The Indian navy flooded a dry dock housing the 112-meter-long submarine to send it out for trials at a ceremony attended by Prime Minister Manmohan Singh.

Singh called it a "historic milestone in the country's defense preparedness"?as the 6,000-ton INS Arihant (Destroyer of Enemies) was named in the southern port city of Vishakhapatnam.

India does not seek to threaten anyone, Singh said at the ceremony. "Nevertheless, it is incumbent upon us to take all measures necessary to safeguard our country and to keep pace with technological advancements worldwide."

The vessel will undergo two years of sea trials in the Bay of Bengal before being commissioned for full service.

Until now, only the United States, Russia, France, Britain and China had the capabilities to develop nuclear submarines.

The milestone is likely to rattle neighboring Pakistan, which has fought three wars with India, two of them over control of the Kashmir region, since they won independence from Britain in 1947.

But India is looking beyond the old rivalry, asserting itself as a power on the Asian and international stage, according to Uday Bhaskar, a former naval commander and director of the National Maritime Foundation.

The US, in particular, has encouraged India's role as a possible counter to China, stepping up exercises with the Indian navy and selling the South Asian nation an American warship for the first time in 2007. American defense contractors - shut out from the lucrative Indian market during the long Cold War - have been offering the country's military everything from advanced fighter jets to anti-ship missiles.

Still, it could take three to five years for India's submarine to become operational, after undergoing sea trials and getting fitted with a nuclear reactor, surveillance equipment and ordnance, said Bhaskar.

The submarine will be capable of launching nuclear weapons, Bhaskar told the Associated Press.

That would complete India's strategic triad for nuclear weapons - giving them the capability of delivering them from the air, from ground-based mobile platforms and from the sea, said Rahul Bedi, a defense analyst with Jane's Defense Weekly, a magazine reporting on military affairs.

India's state-run Defense Research and Development Organization could take two to three years to indigenously develop cruise and ballistic missiles, which can be fired from the submarine, Bedi said.

"India can't buy them from the international market as these are prohibited weapons," Bedi told the Associated Press.

India has modeled its submarine on Charlie-class vessels that it leased from the Soviet Union between 1988 and 1991, Bedi said.

India is leasing another nuclear submarine from Russia for 10 years. It is expected to arrive by early next year.

AP-AFP