The S-300 is another story entirely. It gives the Iranian military a significant strategic advantage against regional states and significantly complicates US air operations in the airspace protected by the S-300. The S-300 is the most advanced SAM system available for export to potential enemies of the United States, and significantly alters planning assumptions for potential US military operations. The S-300 may prevent the US from attaining air superiority as quickly as it has in the past, protracting air operations and potentially increasing the risk of losing aircraft and pilots.