India and Russia signed a number of deals including nuclear energy, railways and fertilisers.New Delhi:  India will finally acquire the S-400 Triumf, arguably the world's most lethal surface-to-air missile system, from Russia, brushing off a threat of sanctions from the US.

The $5-billion pact was signed between Prime Minister Narendra Modi and Russian President Vladimir Putin this afternoon along with a raft of other agreements ranging from nuclear power to space exploration.

In its first reaction to the deal, US said it did not want to hurt military capabilities of its "allies or partners".

In a joint address after the bilateral meeting with Mr Putin, PM Modi said, "Russia has stood by India through time and has played a crucial role In India's growth story."