You wake up one morning and find out 3 American cities have been nuked by what we suspect are Islamic terrorist cells.
Who do you nuke in response?
Answer: No one.
Iran because they been calling for the destruction of Israel and the US. Then we watch china and russia to see if they launch a counter attack,if they do then we have a full scale nuclear war. Thats what will happen. We wont sit on our ass and take nuclear damage even if we have to nuke the wrong nation. It will be Iran,russia, or china that will be behind said nuclear devices.