S-400 Triumf or SA-21 Grower is a surface-to-air missile system from Russia. It is the 4th generation of long range SAMs from Russia, succeeding the S-200 and the S-300. It is considered superior to USA’s THAAD (Terminal High Altitude Area Defense system). It is regarded as the most dangerous operationally deployed MLR SAM (modern long-range SAM). It can engage with a range of aerial targets like UAVs, aircrafts, etc.