Induction of the S-400 Triumf advanced air defence missile system from Russia will be a game changer in the region. Talking to FE ONLINE, Air Marshal (retd) Anil Chopra said, \u201cThe system consists of four separate missiles that cover the entire range and altitude envelope from close quarters to nearly 570 km for heavy bombers and shorter ranges for incoming missiles.\u201d \u201cEach unit will have up to 32 missiles on launchers at any time. It is expected that two units will defend the National Capital Region and another two cover the Mumbai Baroda Industrial corridor,\u201d Chopra added. The system is already operational in Russia and under induction in China, and India will become the third country in the world to have S-400 Triumf advanced air defence missile system. The deal is expected to be inked at the end of delegation level talks between Prime Minister Narendra Modi and the Russian President Vladmir Putin on Friday in New Delhi. In 2015, The Defence Acquisition Council under defence minister Manohar Parrikar had cleared the purchase of $ 5.5 bn S-400 Triumf advanced air defence missile system from Russia in December 2015 through government to government route. In 2018 July the Defense Acquisition Council (DAC) headed by defence minister Nirmala Sitharaman had cleared the agreement to purchase five S-400 air defense missile systems from Russia with minor changes. Though negotiations between the two sides have been going on since 2015, however, in recent months it got stalled due to Washington\u2019s Countering America\u2019s Adversaries Through Sanctions Act (CAATSA). In a recent interaction with the media in South Block, Sitharaman responding to media had said, \u201cWe made it clear that CAATSA was a US law and not a UN law. Negotiations for the (S-400) missiles have been on for several years.\u201d As reported by FE ONLINE earlier this will also be the biggest deal between the two countries since 2011, when India had ordered 140 Su-30 MKI fighter planes for the Indian Air Force (IAF). BOX Based on the information in public domain, for the Indian Air Force which is dealing with an acute shortage of fighter planes, this missile is not only an absolute need but is also useful for its offensive defence strategy. The S-400 is an integrated, highly-mobile system of radars and missiles of different ranges to address multiple threats. A single unit, consisting of eight launchers, 112 missiles and command and support vehicles. According to India Today report, \u201cThe 'Tombstone' radar can acquire up to 300 targets nearly 600 km away.\u201d It means these missiles from different locations can look deep inside Pakistan and keep an eye on any aircraft taking off on the other side. On the Eastern border with China, the missile can monitor planes taking off. \u201cThe system has four different missiles, from the 400-km range 40N6 which can knock out early warning aircraft, fighter jets and tactical ballistic missiles, to the 100-km range 9M96E which can neutralise manoeuvring targets like air-launched cruise missiles and smart bombs.\u201d Once the missiles are inducted in the IAF, multi-role fighters which are currently being used for air superiority role can then be used for other roles like air-to-ground missions. This missile system is also critical to IAF\u2019s India Integrated Command and Control System (IACCS) which is expected to provide a comprehensive picture of Indian airspace by linking all ground and airborne sensors and air defence assets into a single grid. Besides plugging the major gaps in the IAF\u2019s air defence, the system will give a composite air situation picture integrating all air force, navy, army and civilian radars.