|According to what I am reading, many experts think that Iran will have nuclear weapons in 2006. Others are more optimistic. That means that if we are going to act, it must be in 2005 or 2006.
An air strike is always a possibility, but it is so easy for the Iranians to move much of their program underground that it is doubtful that it can solve the problem. At best, it will delay the problem giving us more time.
A more realistic solution, but still short of all-out invastion would be a "Khuzestan Incursion" scenario. Khuzestan is the southwesternmost province in Iran. It is about the size of Massachusetts. It is on the Persian Gulf and borders Iraq. While most of Iran is covered by high mountains, Khuzestan is a low-laying plateau. These mountains effectively isolate the province from the rest of Iran. Most importantly, this is where virtually all of Iran’s oil fields are located.
The "Khuzestan Incursion" scenario would consist of the following. Once Iraqi elections have been held and the insurgency has been cut down to a small enough level that the Iraqi army can handle it, the US moves half of its occupying army to southeast Iraq. This force would consist mainly of Mechanized Infantry divisions.
This force would rapidly take over the province and hold it. Any Iranian counter-attack would be forced to go through the narrow mountain roads, making them very vulnerable to air strikes. Once the US Army has taken control of the province, the president gives the following ultimatum.
1. Iran must destroy all WMD weapons and facilities, allow UN arms inspectors for verification, and promise never to seek WMD.
2. Iran must immediately stop funding, training and organizing terrorists groups and promise not to do so in the future.
3. Iran must abolish the Council of Guardians and transfer all its power to elected officials.
4. Iran must hold new parliamentary and presidential elections within two months.
Until Iran fulfills all four conditions the US military will remain in Khuzestan, all the revenue generated from oil sales will be held in a third-party account. When all four conditions are met, the US military will withdraw and the oil revenues will be handed over to the Iranian government. If Iran renigs on any of the four promises, the US military will return.
Without oil revenues, the Iranian economy would rapidly collapse. Given that Iran already has a sizable democratic opposition movement, I think the Iranian government will fall quite quickly. Rapid elections would create a very short political transition period. Since the US military will hold only a small part of the country, it will have no responsibility to oversee security. The Iranian military and police can maintain these duties.
The Iranian army might try to counter-attack with a massive assault on Iraq, but I can’t see how that would get very far if they have no oil revenues. They would be devastated by American oil power.
The only potential problem would be if a sizeable enough proportion of the Iranian military, police and judiciary remain loyal to the mullahs and are willing to fight an insurgency. This would make a civil war possible and the USA might need to intervene in Iran proper. A US airborne division flown into Teheran would tip the balance towards the rebels in the capital, but some of the loyalist military could retreat into the mountains to fight a guerilla war. My guess is that rebel Iranian military units could handle the situation, but we might need to give them large amounts of military aid, training and advise.
Overall, I see the chances of success high with few American casualties. And I see a low likelihood that it would turn into a long-term occupation draining American resources.