The Iranian regime is once again trying to procure the Russian made S-300 air defense missiles, even after they had claimed that their Islamic revolutionary engineers could manufacture the S-300 system in Iran without any foreign assistance. Turns out, those bogus claims weren't true.
The Iranian Air Defense Forces have some modern air defense systems such as the Russian built Tor M-1 and legacy air defense systems such as US made I-Hawk MIM-23, or Russian built SAM-6 and S-200 systems.
Almost all of these air defense systems are designed to deal with low to medium altitude targets, save for the legacy S-200 of which Iran has a handful. It must be noted that some of Syria's Sa-17 air defense systems have found their way to Iran through Lebanon's terrorist group Hezbollah which upon arrival, were given a new paint scheme and an Arabic name 'Raad.' Some analysts have rightly speculated that Iran has been the actual financier of these expensive purchases by the Syrians in the first place.
Iran's plans to obtain the sophisticated S-300 missile system stems from the regime's desire to protect its nuclear facilities from a possible US or Israeli air strike. The original deal was suspended by the Russian government out of respect for the United Nations' embargoes on the Iranians.
So far their attempts at procuring S-300 have been futile. They must know that S-300 will not stop the Israeli Air Force or the United States Air Force from penetrating the Iranian air space in order to bomb the regime's nuclear weapons facilities.