Although a nuclear deal has yet to be reached with Iran and embargoes remain in place, Moscow has announced that it is ready to send the S-300 air defense system to Tehran. 

If the deal goes through, Iran would have an extremely capable air defense system that could deter the threat of force against Iranian military facilities.

The following Reuters graphic depicts how the S-300 system works. In 2013, Russia delivered the defense system to Syria, which contributed to deterring Western intervention in the country. 

The S-300 is comprised of four road-mobile vehicle classes that work in tandem to detect and destroy aircraft. The missile launcher vehicles have a range of about 93 miles, can fire at multiple targets, and can down aircraft flying as high as 90,000 feet. 

Iran's acquisition of S-300 systems would be "a complete game changer for all fourth-gen aircraft [like the F-15, F-16 and F/A-18]. That thing is a beast and you don't want to get near it," a senior US Marine Corps aviator told The Daily Beast.