The first reaction that occurs when the issue of an Israeli and/or American attack on Iran's nuclear weapon development program is discussed is a possible counterstrike by Tehran. Aside from missiles being launched at Tel Aviv, interdiction of shipping through the Strait of Hormuz rushes to mind.
A successful effort in this regard cuts off a large portion of the world's crude oil supply, including Iran's own exports. The Russians would gain from their increased oil supply role, but it's unclear how that act would aid Iran's military situation. At least it would give Tehran the satisfaction of being able to strike back against the United States. Obviously closing down the Strait harms the Israelis not at all other than getting Middle East oil consumers mad at them. The Arab producers already are.
Iran's dependence on imported refined petroleum is an obstacle to their seeking to close waterway traffic in the Strait and a key argument against their use of that tactic. Granting that Tehran might believe it can develop alternate sources via land if necessary, the feasibility of closing down the Strait of Hormuz is certainly open to question.
This subject has long been a subject of defense studies. One of the most knowledgeable individuals in this field is Chester "Chet" Nagle, author of the critically acclaimed Iran Covenant. A graduate of the U.S. Naval Academy and Georgetown Law School, Dr. Nagle was formerly the military advisor to the National Security Advisor of Oman and as such participated in a joint U.S./UK/Oman assessment of risks relative to any Iranian effort to close the Strait. In appropriately salty yet definitive language. Nagle has characterized any Iranian blockade effort as "…a hell of a lot easier said than done."
It's clear that Iran does not have the naval resources for a classic blockade of the Strait. For a short while, however, before being eliminated, its land to sea missile defense systems might cause some difficulties. Beyond that Iran would have to physically obstruct the passage. One idea that has been posed is to sink ships -- preferably VLCC size -- to block the channel. Nagle points out that this is just not feasible as the Iranians would have to stack them several ships high and wide. A quick look at the sea charts proves that out.
Mining is the priority weapon. But that would have to be done in Omani waters, for large vessel navigation must go through their deep channels rather than the Iranian lanes. This adds another international wrinkle, but the Iranians might not care much about such niceties. Iran can choose to lay the mines several ways. Aircraft can do the job, but there is no intelligence that shows the Iranian Air Force has the experience and capability to drop the appropriate mines.
Chet Nagle has indicated that perhaps the best way to clandestinely place mines would be by submarine. The U.S. did this in Haiphong harbor and it would work in a narrow waterway such as Hormuz. But to use this option the Iranians must have subs that have practiced the technique and, preferably, self-propelled mines. Nagle doesn't believe the Iranian Navy is capable of this op.
What the Iranians do have is many types of boats and ships capable of introducing mines into the water. It is generally agreed that the traditional moored mine is difficult to lay expertly, and easy to sweep. Nagle points out that bottom mines are easy to lay, hard to find, and, given their magnetic, acoustic and pressure sensors, very hard to sweep. But he notes these are "bottom" mines and thus will not threaten a ship far above. There are very effective classified mobile mines, he says, but Iran would have to have become proficient in their use and deployment.
The counter measures to all these mines are minesweepers and minesweeping helicopters, of course. Chet Nagle is very direct in his comments on this. "The best counter measure is to heavily bomb the bases from which the minelayers might come as well as sinking the minelayers en route. That takes planning and resolve."
Perhaps the most "Persian" of tactics would be if Tehran's propaganda machine churned out statements that they had mined the Strait without actually doing so. This would move the big insurers to declare the waterway a war zone with its predictable effect on prices and the world economy. The counter to that move would be for the U.S. and UK navies (along with NATO and Gulf forces desirous of participating) to deploy in full battle mode to interdict by force if necessary any and all Iranian navy and air assets.
Yes, blocking the Strait of Hormuz is far easier said than done. But it takes something more than the threat of sanctions to make Tehran aware of that fact.