Israeli officials in June called on Russian Prime Minister Vladimir Putin to delay the delivery of the S-300PMU missile system to Iran. Moscow, for its part, said it has not delivered any of the S-300 units it agreed to sell Iran in 2008 under an $800 million contract.
The S-300 system is considered one of the most effective all-altitude air-defense systems in the world. It could make Iranian airspace impervious to modest attacks.
Russian news agency RIA Novosti says the S-300 air defense system is vulnerable to the F-35, Lockheed Martin's fifth generation of stealth fighters.
Israel, the report says, had sent a request to the U.S. Defense Department to purchase at least F-35s with the goal of penetrating the S-300 system in Iran, the Iranian state-funded broadcaster Press TV reports.
The Israeli F-35s would replace older F-15 and F-16 fighters. The S-300 is comparable to the U.S. Patriot missile, boasting an intercept range of 16 miles.