Quote from pspr:
Iran is going to practice shutting down the Straight of Hormuz. I suspect the U.S. Navy will at least shadow this exercize and prevent any disruption in shipping that might occur. This test by Iran could be very dangerous and even start a conflict should they try to push the U.S. out of the way
Also, the airspace over Iraq is now open for any Israel attack on Iran. Iraq has no airforce and we have ceased to patrol the airspace.
In a real conflict Iran could not actually block the Straights to shipping because the tankers will likely form up into convoys under USN escort.
What Iran can do is affect the price of crude oil by dropping a few mines into the Straights and perhaps conducting some harrassment of shipping by armed speedboats. Iran's Air Force is virtually nonexistant so they probably wouldn't be a factor.
Also, of course, Iran could fire its medium-range missiles towards Israel or Turkey or both. It could induce its proxies Hamas and Hezbollah to fire thousands of missiles from Gaza and southern Lebanon at Israel. Likely a reoccupation of Gaza would occur but that is another subject.
But that is about it. Honestly there aren't any other significant military actions Iran can take towards the West except to continue to try to develop nuclear weapons and distributing them to its allies Syria and whomever else is so foolish as to throw in with them.
Russia and China will only support Iran up to a point. Neither of them is interested in a hot war with the USA. Both of them have become incredibly uncomfortable with our hegemony in the region and are doing their level best to muck things up but not in an overt manner. The russians have a large fleet at a Med port in Syria so there is some eyeball-to-eyeball contact between them and the USN already but I just don't anticipate a real problem with them.
China is more worried about its own backyard (south China Sea) and has lots of other problems to cope with. They don't want us hammering a country that supplies oil to them. Perfectly understandable but I don't think they will intervene overtly either.
Even an arch-liberal like Barrack Obama will have to act in our interests eventually and it appears to me that he already has given the amount of stuff that is blowing up in Iran.
Once Syria and Iran are brought back to some kind of secular civilian governance the region will become quite a bit less dangerous and the other serious problems can be worked on.
Personally I'm torn between my agreement with Ron Paul that we should stop being the global policeman and the recognition that a nuclear-armed Iran is going to be a real nightmare for the world.