They are flexing regional muscle.

I would like to say that it would be a good day when we don't really need much from them, but if the US disengages the Middle East, the Iranians or their surrogates will eventually try to make good on their goals of world domination. It's not like it is any big secret, it's in their religious literature. Conquer and dominate everyone they can, terrorize everyone else until they can be conquered.