New Delhi, Aug. 8 -- Armed with three types of missiles to create a layered defence, the S-400 Triumf (NATO reporting name: SA-21 Growler) is an air defence missile system developed by Almaz Central Design Bureau of Russia. Alexander Lemanskiy of Almaz-Antey was the Chief Engineer on the S-400 project. Essentially an upgrade of the S-300 series of Surface-to-Air Missile (SAM) systems, the system, August 2007 onwards replaced the S-300P and S-200 air defence systems of the Russian Army.

A deal to purchase S-400 systems by India was first reported in October 2015. On 15 October 2016 (during the BRICS Summit) India and Russia signed an Inter governmental Agreement (IGA) for the supply of five S-400 regiments to India. On 1 July 2018, the Defe...