If Barack Obama thinks that such a catastrophe can be avoided by sitting down and talking with the leaders of Iran, then he is repeating a fallacy that helped bring on World War II.
In a nuclear age, one country does not have to send troops to occupy another country in order to conquer it. A country is conquered if another country can dictate who rules it, as the Mongols once did with Russia, and as Osama bin Laden tried to do when he threatened retaliation against places in the United States that voted for George W. Bush. But he didn't have nuclear weapons to back up that threat-- yet.
America has never been a conquered country, so it may be very hard for most Americans even to conceive what that can mean. After France was conquered in 1940, it was reduced to turning over some of its own innocent citizens to the Nazis to kill, just because those citizens were Jewish.
Do you think our leaders wouldn't do that? Not even if the alternative was to see New York and Los Angeles go up in mushroom clouds? If I were Jewish, I wouldn't bet my life on that.
What the Middle East fanatics want is not just our resources or even our lives, but our humiliation first, in whatever sadistic ways they can think of. Their lust for humiliation has already been repeatedly demonstrated in their videotaped beheadings that find such an eager market in the Middle East.
None of this can be prevented by glib talk, but only by character, courage and decisive actions-- none of which Barack Obama has ever demonstrated.