Can Iran Close The Strait Of Hormuz?

Strait of Hormuz. Google Maps.

One-third of the world’s seaborne oil is shipped through the Strait of Hormuz. That’s approximately one-fifth of all oil production worldwide (including oil transported overland by pipeline, rail, and truck). Tanker ships load crude, liquefied natural gas, and other petroleum products from Persian Gulf terminals which include those belonging to Iran, Iraq, Saudi Arabia, Kuwait, Qatar, United Arab Emirates (UAE), and Bahrain, before navigating the strait on their way to destination ports overseas.

China and India, which together comprise 35% of humanity (CIA World Factbook), import vast amounts of oil from the Middle East, most of which originates in the Persian Gulf and therefore must pass through the strait. They are both heavily dependent on Persian Gulf oil. Many other countries also purchase crude oil from the Persian Gulf, including Japan, South Korea, the United States, and much of Europe.

This world of ours runs on oil. To say that the strait is vitally important to the global economy, and thus is militarily important, is sublime understatement. The Strait of Hormuz is regarded as one of the most, if not the most, strategic chokepoints on Earth.

As Stratfor Worldview indicates, there isn’t alot of room for tanker ships or warships to maneuver:

The Strait of Hormuz is 21 miles across at its narrowest. The shipping traffic corridor itself is a mere 6 miles wide, with 2 miles each for incoming and outgoing traffic, separated by a 2-mile buffer.

The shores of Iran form one side of the strait, while on the other side the Musandam Peninsula (shared by the UAE and Oman) thrusts north-northeast like a dagger toward southern Iran. Separating the Persian Gulf from the Gulf of Oman (and ultimately the Indian Ocean), the strait forms a 90 degree bend around the Musandam Peninsula in an Iranian ‘bowl’, such that ships in the strait are closely surrounded on three sides by Iranian territory. Iran is in the perfect position to close the strait by force if it so chooses.

In fact, the Iranian government has periodically threatened to close the strait (basically, whenever they’re under pressure) since the 1979 revolution brought them to power. Due to the impending reintroduction of sanctions by the United States, the Iranians are under tremendous pressure once again. The government is highly dependent on revenue from oil exports and the value of the Iranian rial is crashing in relation to the U.S. dollar, Reuters reports. As of July 29, the rial is now worth less than half of what it was worth in April.

To better understand the current threat, let’s take a look at Iran’s history of interfering with Gulf shipping. During the Iran-Iraq War (1980-1987) both countries depended heavily on income generated by crude oil sales to pay for the war against each other. At the start of hostilities, Iran destroyed Iraq’s only oil terminal. Saudi Arabia and Kuwait, no friends of Iran, assisted Iraq by accepting pipeline crude from Iraq and shipping it out of their own terminals. This allowed Saddam Hussein to keep money flowing in for the fight against Iran. (Ironically, after the war with Iran was over, Saddam expressed his appreciation for their help by invading Kuwait and seizing their oil fields).

Their own oil terminal destroyed, Iraq resorted to attacking Iranian tanker ships, primarily with air power, in an effort to deny the enemy war financing. Later in the war, Iran also turned to attacking tankers and other types of vessels (regardless of what flag they flew) in an effort to stop the Saudis and Kuwaitis from aiding Saddam’s war effort against Iran. However, the Iranians didn’t limit themselves to air strikes alone. They also employed various weaponry at different times, including land-based missiles, frigate-based guns (cannons), high-speed patrol boats and speedboats armed with machine guns and RPGs (rocket-propelled grenades).

That strategy became known as the Tanker War (1984-1987). By mid-1987 the U.S., the U.K., and France, were providing naval escorts (convoy protection) for commercial shipping through the strait and in the gulf.

As one of many tactics used in the Tanker War, Iran began to use mines in the Persian Gulf as early as May, 1987, to attack shipping, according to the U.S. Naval Institute. Eventually these moored mines were found intentionally anchored in the shipping lanes and as far south as the Gulf of Oman.

In September, 1987, U.S. forces caught an Iranian minelayer vessel, the Iran Ajr, in the act of laying mines. The ship was attacked and siezed. Later it was scuttled, but not before the mines aboard had been examined.

On April 14, 1988, the USS Samuel B. Roberts, a guided missile frigate, was damaged and nearly sunk by an Iranian mine in the Persian Gulf while on escort duty (Operation Earnest Will). U.S. forces cleared the minefield where the Roberts had been struck. A comparison of serial numbers between these mines and the mines found aboard the Iran Ajr the previous September proved that it was an Iranian mine that had nearly sunk the Roberts.

In response, the United States launched Operation Praying Mantis on April 18, 1988. In the one-day action, the U.S. Navy quickly sank one Iranian frigate, one gunboat, and three Boghammars (speedboats). Two militarized oil platforms used by Iranian naval forces were also destroyed. A second Iranian frigate was severely damaged and nearly sunk. Disabled, that ship had to be towed into port for extensive repairs. These were heavy losses for the small force that Iran’s navy was at that time.

Operation Praying Mantis was important because it demonstrated to Iran that the United States would not tolerate the closure of shipping lanes in or around the Strait of Hormuz, by mines or any other means. Apparently the message was received. Iran has not attempted to close the strait since, although they’ve threatened to many times; (Daily Mail Online),(Middle East Affairs).

Recently, Iran has again threatened to close the strait. In early July, Gulf News reported that Iranian President Hassan Rouhani said, “The Americans say they want to reduce Iranian oil exports to zero… It shows they have not thought about its consequences”. This statement was quickly followed by Revolutionary Guards’ Al Quds Force commander Qassem Solaimani, who indicated that they were ready to block oil shipments through the strait if sanctions are implemented against Iran. Al Arabiya noted that, “Iranian commander of the Islamic Republic Revolutionary Guard Corps (IRGC) Major General Mohamad al-Jafari announced that the Strait of Hormuz either is for everyone or it is not for anyone”.

On July 21, Reuters (via Jerusalem Post) stated that, “Iran’s supreme leader [Ayatollah Ali Khamenei] on Saturday backed President Hassan Rouhani’s suggestion that Iran may block Gulf oil exports if its own exports are stopped, according to his official website.”

However, not all Iranians agree that this would be a good idea. Al Arabiya:

Iranian former IRGC naval commander Maj. Gen. Hossein Alaei criticizes threats issued by Iran President Hassan Rouhani and a number of military officials to close the Strait of Hormuz if new oil sanctions are imposed against Tehran.

In an interview with Iranian news agency IRNA, Alaei considered such kind of statements as “not well thought out,” adding that “Iran is unable to close the Strait of Hormuz, but America is capable to reopen it.”

No doubt Major General Hossein Alaei, former IRGC naval commander, remembers the lessons learned from Operation Praying Mantis.

Among the nations taking the Iranian threats seriously are China and the United States. Al Arabiya wrote on July 6, “Iran prompts China anger over threat to block Strait of Hormuz oil exports”. In the GPF Daily Memo, dated July 26, 2018, Geopolitical Futures wrote, “the U.S., Egypt and Gulf states began demining exercises in the Red Sea – these kinds of exercises would immediately be put to use in the event of an oil blockade.”

If Iran decides to close the Strait of Hormuz, it will be an act of desperation – the kind which rogue governments make when they have nothing left to lose.


Note that the Stratfor Worldview article referenced above in the fourth paragraph, and again here, is 10 years old but provides a likely, if dated, description of Iran’s military capabilities in and around the strait. It’s worth reading to get an idea of the preparations Iran has made in the thirty years since the Tanker War to control the strait in the event of war.

Iran: The Threat to the Strait of Hormuz (Stratfor Worldview, Jul 1, 2008)

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