With international sanctions on Iran now lifted, it was a matter of time before Russia and Iran came to terms on a new contract for SA-10 (S-300) surface to air missiles. A contract worth $800 million had been signed by the two nations in 2007 but Russia froze it in 2010 after sanctions were applied to Iran. It is not yet clear which variant of the SA-10 that Iran will purchase. For months the US, Israel and the Gulf States have been worried that the lifting of sanctions against Iran would trigger a massive re-armament program by Tehran. It appears that the first phase is underway now.
The aforementioned nations are also alarmed by the quality of the weapons systems that Iran is beginning to purchase. Iranian and Russian officials have downplayed the SA-10 sale, stating that the system is defensive in nature and cannot be used to threaten other nations in the region. On the surface, this is somewhat correct. SAMs are not offensive weapons per se, but the newer variants of the SA-10 have extended ranges. If Iran decided to position SA-10 batteries close to its coastline it could effectively shut down the airspace over the Persian Gulf, and sections of the Arabian Peninsula. Saudi Arabia has asked Russia more than once to shelve the deal with no success.
For the United States and Israel, the SA-10 purchase presents a unique dilemma. Iran is quite likely bolstering its air defenses to deter possible air strikes against its nuclear facilities should the nuclear deal fall apart. If that day ever comes, US or Israeli aircrews will have to fight their way past an increasingly effective and modern integrated air defense system in order to reach their targets.
*Note-I originally planned to post the first part of First Strike tonight, followed by this update tomorrow. At the last minute I decided to change the order. First Strike will be posted tomorrow evening*