Most Iranian military threats are more propaganda than reality. Take, for example, their threat to shut the Straits of Hormuz (where ships exit the Persian Gulf and enter the Indian Ocean). Some 40 percent of the worlds oil shipments pass through the Straits of Hormuz, 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).
The Iranian problem is that they have a small navy, an obsolete air force and a poor track record when it comes to shutting down tanker traffic in the Persian Gulf, or the Straits of Hormuz. They tried once before, in the 1980s, when they were at war with Iraq. The two nations began attacking each others tanker traffic early on, in an attempt to cut off each others oil sales (and, thus, military purchases). Iran didn't want to shut the Straits of Hormuz, because it needed the oil revenue more than Iraq (which was getting billions in aid from other Arab states) did. So each country concentrated on attacking shipping in the Persian Gulf. Over 500 ships were attacked, 61 percent of them tankers. Only 23 percent of the tankers attacked (mainly with the types of anti-ship missiles that are still in use) were sunk, or immobilized. The attacks, using fighter-bombers and warships, only hit about two percent of the ship traffic in the Gulf. Iran lowered its oil prices to cover the higher cost of ship insurance, and in 1986, Russia and the United States intervened to protect Kuwaiti and Iraqi tankers (which were taking most of the damage).
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 Arab states have lots of mine clearing equipment, and more numerous air and naval forces than Iran. In addition, there is the United States and NATO forces in the area. If Iran tried to shut down the Straits of Hormuz, it's more likely that 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.
The UAE (United Arab Emirates) controls one side the entrance to the Gulf (the Straits of Hormuz). Iran is on the other end, and both nations dispute ownership of some islands in the middle. The UAE is a confederation of small Arab states at the southern end of the Persian Gulf. But the UAE is part of a larger coalition that includes all the Gulf Arab states. The combined military forces of the coalition is much larger than what Iran has.
Iran, and its potential opponents are continually trying to devise new weapons and tactics for fighting a war in the Persian Gulf. Iran concentrates on methods for disrupting tanker traffic, while everyone else seeks ways to derail Iranian attacks, and keep the traffic moving. Studies, including wargaming, have shown that Iran is in a very unfavorable position. In fact, the most damage likely to result from Iranian aggression, would be an increase in world oil prices, because of the loss of Iranian exports. In the near future, even that threat is likely to be countered by increased Iraqi production.