Trust me, they wont attack US because that means that they will loose everything, US has enough nukes to destroy China multiple times. They will not risk such thing just because of Iran. Depends on how it's done, but I'm sure that it will be less than 100 million. They have to sacrifie every bit of their land which they most likely will not do. So? Russia also do exercises with America. Poltical statements makes them a bigger threat. All nukeowners pose a threat though. One misstake can start a new WW3. This will happen sooner or later but Iran will not be the most important factor for this outbreak. This is irrelevant, Iran doesn't have any nuke now.
We appear to have missed our timetable to begin this war. Someone notify Gates that Rumsfeld dropped the ball yet again