Iran has been the instigator or financier of almost all global terrorism that affects US interests for the last 50 years. It's not like that's a secret.
The only reason why the US has been dealing with the effects rather than the cause for so long is best illustrated by the mess we have now.
I guess we can be a little thankful this is bogging down because next on the list is Russia and the little proxy war between the US and China going on in Ukraine.