In a significant step towards completing the nuclear triad available with a few nations, India has successfully test-fired a nuclear-capable ballistic missile launched from an underwater platform with a range of over 2,000 kms.

The missile, which can be launched from submarines, was test-fired yesterday in the Bay of Bengal and all parameters were met, Defence Ministry sources said.

This is the longest range missile in the underwater category to have been developed by India.

With this development, India has developed the capability of launching long-range nuclear-capable missile from surface, air and underwater.

Defence Minister AK Antony has congratulated the team of scientists involved in the tests.

Launch from a submarine and integration of the three types of capabilities will mean completion of the nuclear triad, which is available only with a few countries like the US, France, Russia and China.

The submarine-launched ballistic missile (SLBM) is being readied for deployment on various platforms including the around 6,000-tonne indigenous nuclear submarine INS Arihant which will soon be ready for sea trials, sources said.

The missile is part of the family of underwater missiles being developed by DRDO for the Indian strategic forces' underwater platforms.

The DRDO has already developed the BO5 missile, which can strike targets at a range of around 700 km.

India has a no-first-use policy for nuclear weapons and the development of an SLBM boosts its retaliatory strike capability, experts said.