The S-300 is a series of Russian long range surface-to-air missile systems produced by the Almaz Scientific Industrial Corporation all based on the initial S-300P version. The S-300 system was developed to defend against aircraft and cruise missiles for the Soviet Air Defence Forces. Subsequent variations were developed to intercept ballistic missiles
“Iran has received four S-300 Russian long range surface-to-air missile systems even though Moscow decided not to implement a contract it had with Tehran to deliver them because of the new United Nations sanctions.”