In order to answer this, we have to look briefly at what realism is. Realism holds that states must do things that are in their national interest. States must not act for reasons other than the desire to improve their security. States are not to do things like trying to promote international law or democratization. Those things cannot help a country become more secure and security is the major interest of the state.
With that in mind, what I would propose as an advisor would be containment. I would propose that we think about what Iran’s actions really mean for us. We should realize that Iran’s nuclear weapons cannot really pose much of a threat to us. We can presumably deter them from actually using their weapons because we are so much more powerful than they are. I would propose that we ignore the fact that they broke international law because that has little material effect on us. Instead of worrying about the fact that they broke this law, we should focus on preventing them from harming our interests. We should make clear that any aggressive acts on their part will be met with a very strong actions on our part. We must make clear that we will use our military power to prevent them from using their nuclear weapons or conventional forces to disrupt our interests.
So, my proposal would be Cold War style containment where we acknowledge that we cannot make them do what we want, but we can prevent them from hurting our interests.