India and Russia Saturday inked 16 pacts, including two key defense agreements, after Prime Minister Narendra Modi met visiting Russian President Vladimir Putin on the sidelines of the 8th BRICS Summit in the western state of Goa.

One of the two key defense deals included the sealing of a five billion U.S. dollars pact to procure Russia's most advanced anti-aircraft defence system -- S 400 Triumph, which will provide India a ballistic missile shield.

This system can track some 300 targets and shoot down around three dozen simultaneously over a range of 400 kilometres. The radars are so powerful that they can even detect stealth aircraft of enemy countries.

Under the other defense deal, India will initially acquire and subsequently produce Russian Kamov Ka-226 T light utility helicopters. Both India and Russia have also decided to conduct a military conference every year.

Other agreements across multiple sectors included developing smart cities in the southern state of Andhra Pradesh and northern state of Haryana, and for developing transport logistics systems for cities in these two states.

Another important agreement was signed for the joint study of a gas pipeline to India from Russia. A pact was also inked between India's space agency and the Russian state space agency on collaboration in space technology.

Addressing a joint media meet, the Indian Prime Minister referred to Russia as an "old friend" and said their bilateral meeting "clearly establishes the special and privileged nature of strategic partnership between the two countries".

"They also lay foundations for deeper defense and economic ties in years ahead. The agreements on manufacturing of Kamov 226T helicopters, constructions of frigates, and acquisition and building of other defense platforms are in synergy with India's technology and security priorities," he said.

India is currently undergoing a 100 billion U.S. dollars upgrade of its mostly Soviet-era defense equipment. Though it earlier used to completely depend on the erstwhile Soviet Union for military hardware, it has turned to the U.S. in recent years for supplies.