It is particularly telling that the U.S. contingency plan for 'dealing with' Iran has but one military strategy - nuke 'em. It is the only military strategy being discussed. Bringing democracy to Iran isn't even on the table. 

Why? Because we took a fledgling democracy away from Iran in the early 1950's and installed a military dictatorship. Forcibly installing precisely the kind of government which we destroyed wouldn't go over well with the Iranian people. Forcibly installing any kind of government probably would not go over well with the Iranian people. The last time we did this, we brought them the Shah - who was arguably the most vilified human being on the planet until they finally were able to dump him in the late 1970's.

For those that are too young to have studied these events, it all came about because of a British oil conglomerate. They pumped the oil and shared the profits with the Iranian government (and people). Except this particular oil company was a bit corrupt (I'm shocked!). They cooked the books and weren't sharing all the money. So the government did what any government would do under the circumstances - they kicked out the corrupt thieves and took their oil back.

This didn't go over well in Washington D.C. You see, our oil companies were bigger than the British companies. What if all the oil-rich lands decided to nationalize all the corrupt oil companies? It wouldn't be good for business. It wouldn't be good for the continuous flow of cheap oil (gasoline was about 22 cents a gallon at the time). So at the urging of a handful of American business executives, the CIA covertly threw a few million dollars into a program to dump the government and take back the oil resources. We brought back the monarchy which had existed prior to WWII.

The Shah rapidly consolidated power and tortured or killed anybody who disagreed with him. In the 1960's the word 'Shah' was synonymous with 'torture'. This is why the Iranians don't particularly like the U.S.

It is therefore ironic that in the early 1970's the Shah nationalized the oil companies anyway. We grumbled a bit, but let him. He gave us long term contracts in exchange, and we really didn't want to mess with him, as he had created the largest military machine in the middle east due to our continued financial support. It was also more important for us to maintain our CIA listening posts and airbases near the Soviet Union than it was to defend the oil conglomerates again. This turned out to be a reasonable decision as Iran was the only Arab country that sent us oil during the 1973 Arab oil embargo; which was to protest our backing of Israel in the Arab-Israeli war earlier that year. The Iranian people would've preferred to join the embargo, but they had no say in the matter. The Shah had absolute control.    

All of this is why the Iranians would never allow a U.S. installed government to exist again. And it is why we have no other choice but to wipe the country off the face of the earth if current negotiations fail. 

What a mess we've created.