Iran's attempting to purchase an air-defense missile system from Russia. Unstated (but implied) is the fact that Russia is seriously considering it.
Because it's a weapon they can hold over our head to prevent us from setting up the ballistic missile defense umbrella over Europe. Never mind that it's meant to prevent regimes like Iran from nuking European nations, and has nothing to do with Russia.
At least, it doesn't from our end.
14 minutes ago