Strategy Page runs down the history of naval mines and explains why Iran is most likely to try using mines to close down the critical Straits of Hormuz to tanker traffic if a new Gulf War begins:
The U.S. and over 30 other nations recently held a joint mine clearing exercise called the International Mine Countermeasures Exercise 2012 (September 16-27). The numerous training events were directed at dealing with Iranian attempts to block the entrance (Straits of Hormuz) to the Persian Gulf. Iran insists it will have no trouble doing this and blocking the export of oil. Some 35 percent of the world’s oil shipments pass through these straits, which comes to about 15-20 tankers a day (plus a dozen or more non-tankers). The Persian Gulf, in general, is a busy waterway. It is 989 kilometers long, and the average depth is 50 meters (maximum depth is 90 meters). Naval mines are Iran’s best bet if they want to shut down the straits.
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The Iranian military is in worse shape today than it was 25 years ago, and would not last long trying to attack ships. That leaves the Straits of Hormuz. This is actually a wide (about 30 kilometers) deep channel. Normally, shipping sticks to narrow (a few kilometers wide) channels, going in and out, to avoid collisions. The main Iranian threat has always been seen as naval mines. The Arab states have lots of mine clearing equipment, and more numerous air and naval forces than Iran. In addition, there are the United States and NATO forces in the area. The problem was that all these mines clearing forces had never practiced under realistic (wartime) conditions. In short, what would everyone do if Iran did mine the straits.
Iran would probably mine the straits if sanctions, or military action, halted all Iranian oil exports. Otherwise, mining the straits would be economic suicide. If Iran tried to shut down the Straits of Hormuz, it’s more likely that effort would fail and the straits would remain open for non-Iranian oil. With the loss of their oil exports, Iran would find its remaining military forces being hunted down and destroyed day after day. Not only would Iranian oil exports be halted, but so would imports. Iran depends on imports of food (over 100,000 tons a week) and gasoline to keep its economy operating.
For an Iranian mining attempt to work they would have to get the mines onto the bottom of the straits and then prevent the rest of the world from clearing those mines. That would be difficult, as will Iranian attempts to plant additional mines. Such attempts would not be impossible as Iran has small submarines and speed boats along with sailors willing to carry out suicidal missions to deliver the mines. Even that may not be sufficient as this sort of fanaticism failed against the Americans in the 1980s. While Iran has worked to overcome their shortcomings, most of the solutions appear to be publicity stunts mainly meant to make the Iranian population feel better.
