In a sense, an Iran without nuclear weapons is a threat to the US and the region. A nuclear armed Iran is a threat far beyond — first to Russia and, further afield, India and China. In fact, at that point it’ll be a middle sized power in search of Allies and a patron. It could easily play all those powers off each other — and even threaten to hook up with the US once more. In fact, a mullah free government would find that move very attractive.

So if there is a “great game” between the other powers and the US as regards Iran, it is perhaps a game the other powers don’t really want to win — if the prize is a nuclear armed neighbor with an unhinged leadership. And perhaps the Iranians, who have longed played everyone else for fools, feel like they are the ones getting played now.