with Iran was a good idea.
But Senator McCain thinks this is a very bad idea.
I don't know to what degree that McCain decided that coordinating with Iran was a bad idea after having heard that SOS Kerry was considering it, but I see his point. The enemy of our enemy does not become an ally. If Iran wants to "protect" key Iraqi cities from ISIL, it's because they would like to maintain or increase their influence. I don't know that if we need to "help" them, there, but I do suspect that there is no way we get any alliance with Iran that's more than transactional, temporary, and liable to have blowback of some kind. Just a feeling.