Joint Chiefs of Staff Chairman Gen. Martin Dempsey sought to downplay the impact of Russia removing a long-standing ban on selling S-300 defensive missiles to Iran, saying the US option to attack Iran remains “intact.”

The S-300 was the cream of the crop of 1980s Soviet long range anti-aircraft systems, something Iran has sought for years because of constant threats by both the US and Israel to attack.

The S-300 has never actually been used in combat anywhere, but is still considered a high-end defensive system. It should be noted that the Russian removal of the ban doesn’t mean Iran will actually purchase the weapons, or that delivery is imminent, as since losing the contract in 2010 Iran has developed some more elaborate internal air defense systems.

No air defense system is absolute at any rate, so Gen. Dempsey is correct in that it doesn’t prevent the US from unilaterally attacking Iran if it wants to, but does increase the risk of losing one or more warplanes in such an attack,