Last I checked the Sunni branch of Islam has been attacking the USA since the 90s and resulted in mass deaths and destruction. And the Sunnis do have an allied nuclear state in Pakistan.
So why am I to concentrate on a threat from Iran that is hypothetical and pushed by theorists who urged the Iraq invasion and got that wrong? That group of fools has yet to get anything right on the middle east. yes, I am looking at you neoocons - failures that you are.
I am suggesting that you concentrate on the entire picture and form a national policy. That policy might be to concentrate on Isis but maybe not. In any event it requires an assessment of the balance of risks and fixing America’s national interests