Are the chickens coming home to roost in Iran? How soon till they land in America?

In reading this article about an explosion in Iran, I wonder if that country isn't starting to experience a turning inward of what appears to be a consistent call to violence against the west and its perceived allies. Maybe not a call but a distinct lack of condemnation that legitimizes it. If it is legitimate to encourage the use of car bombs against your external enemies, how long until your own internal factions realize that these same weapons can be used against you? What worries me more is that, it can't be long until it will be more common in our own country. I'm not talking about some sort of 9/11 style attack but something more akin to the Oklahoma City bombing. I worry that in seeing how effective and disruptive these style attacks are that our own internal dissidents will resort to the same tactics. Maybe we lack people that desperate. I'm not sure.