[SauronOfMordor]

I think this letter is just intended to be some psychological warfare against us in retaliation, just to "get even." Iran is not going to attack us until the day they actually have nuclear weapons (if we allow them to build nukes). If they attack us now, they have no chance of defeating the US military, and they know they would surely lose.

He gave us the "call to Islam", which is supposed to precede an attack. He's telling the whole Muslim world he's going to attack the US. If he doesn't attack, and attack fairly soon, he loses face. Muslims hate losing face (look up "honor killing")

[defenderSD]

Perhaps he would lose face by not attacking, but if he attacks us now he's playing right into our hands (and right into intersecting fields of fire from US air and ground forces.) If he tries a terror attack here inside the US, he'll only strengthen our resolve to implement a regime change in Iran.