How feasible is a blockade?
Iran has only one refinery, and imports almost all of it's gasoline. We would be hurt if they shut off the crude, but they would be crippled.
Interesting point. I would say not very feasible for a number of reasons. First off the confined/shallow waters of the Gulf are not optimal for the blue water USN and our allies. Much of such work, or at least monitoring, would be done by our submarines and the shallow waters are bad news for our boats. We have huge SSNs that need deep water to operate at full effectiveness. Also, shallow water doesn't have the temperature layers for our boats to hide under to help keep them from being discovered.
Carriers in the Gulf are also at great risk from AshMs. Out in the open ocean they would have escorts spread out providing layers of defense, along with their aircraft. Such deployments aren't feasible in the gulf.
OK, so we go out in the open ocean of the Gulf of Oman and catch ships coming out of the Gulf? That would start problems with the countries that own the ships and need the oil. Not just that but the mouth of the Persian gulf, and surrounding waters, are like an ocean super highway. Imagine how many ships you would have to stop, and how many navy platforms needed to complete the mission?
Lastly Iran would probably view it as an act of war and attack the naval vessels. That's not so big a problem but it does beg the question if we go thru all that then why not just attack them first? Why let them control the engagement?
Our allies wouldn't go along with it anyways. They are more interested in selling goods to Iran
http://www.iranfocus.com/modules/news/article.php?storyid=1552 And if they dont even go along with economic sanctions how can we expect the mainland Euros to go along with military force. Which is what a blockade is. The price of oil, after such a move, would increase by factors of "X" and would increase the INTL hostility pointed at us for launching a blockade.
The Chinese and Russians have already said "nyet" to any force against Iran which precludes any U.N. authorization.