Downright scary. Iran with nukes.
I don't get the U.S.'s game on this: Are we really willing to put this off onto Israel (that being, military action to stop nuke development)? We are really going to sit by and watch Iran get nukes?
So far, international action on this has been... inaction. We can't even get the UN Security Council to agree on "tough sanctions.".
Iran won't negotiate on this. It will only forestall. It won't stop until it is stopped from an outside force. If Iran attains nuclear weapons capability, then expect one to come floating up to the shores of Israel sometime soon after that. Heck, maybe even New York or LA. Put a nuke on a boat, have your terrorist friends sail it close to a city of their choosing. Simple.