A "first strike" nuclear attack from America is justified
Doctrine for Joint Nuclear Operations
"Executing a nuclear option, or even a portion of an option, should send a clear signal of United States' resolve. Hence, options must be selected very carefully and deliberately so that the attack can help ensure the adversary recognizes the "signal" and should therefore not assume the United States has escalated to general nuclear war, although that perception cannot be guaranteed."
I have no problem with America announcing to the world, the exact target coordinates in Iran, one hour prior to missile launch.
For obvious reasons, we would not want Russia, China or France to think that they are the target.