A reader writes:
The reality is that Iran doesn't need to actually stop the flow of oil through the Straits of Hormuz in any significant way for the threat to be effective. The mere threat itself has already pushed up the cost of oil a bit, so imagine what happens if Iran managed to sink a single tanker in the Straits. While it might only be one tanker of oil eliminated from global supply, the markets would freak out. The panic would drive up the price of oil, increase Iran's profits, and likely lead to a global recession.
Another writes:
I ran offshore oil field supply boats in the Persian Gulf for a couple of years a long time ago. It is inconceivable that Iran would be able to close the Strait of Hormuz. Three potential ways to do it have been discussed:
– attacking ships with planes, boats, or artillery as they pass through the strait. They've tried this before and failed. The US Navy would destroy any planes, boats, or artillery that tried it. The Iranians might slow it down for a day or two.
– placing mines in the shipping lanes. We are pretty good at sweeping mines. I watched US navy helicopters sweep the Gulf of Suez after Kaddhafi dumped a bunch there in the early 1980s. One boat was damaged out of (we think) several hundred mines dropped.
– sinking ships in the middle. The shipping lanes are 6 miles wide, plus a safety buffer, and about 300 feet deep. You'd have to sink a lot of ships to pile them up that high and that wide.
The Dish 