Accessibility links

Explainer: Iran's Threat to Blockade The Strait Of Hormuz

  • RFE/RL

An Iranian Revolutionary Guards Corps boat during training exercises in the Persian Gulf in 2007

An Iranian Revolutionary Guards Corps boat during training exercises in the Persian Gulf in 2007

A hard-line Iranian newspaper considered to speak for Iran's supreme leader has come out in support of closing the Strait of Hormuz in the Persian Gulf, the world's most important oil-shipping lane, as punishment against countries that have sanctioned Tehran over its suspect nuclear program.


A December 13 editorial in "Kayhan" asks, "Why has the Islamic Republic of Iran not used its unchallengeable right till now, when there is a conspiracy of imposing sanctions against our country's oil?"


The piece comes a day after an Iranian lawmaker reportedly said the country's military was planning to hold drills to practice closing the vital shipping passage. The news agency ISNA quoted deputy Parviz Sorouri as saying, "If the world wants to make the region insecure, we will make the world insecure."


Julian Lindley-French, a professor at the Royal Military Academy of the Netherlands, says Iran's intent appears clear. "If this threat was carried out, in a sense -- denial of access through the Strait of Hormuz -- then [Iran] will be on a direct route of confrontation with the West and, indeed, many of the regional powers," he says.

That's because the strait -- which runs mainly along Iran, but also touches Oman and the United Arab Emirates -- is the only way for Persian Gulf oil to reach the open sea. An estimated 15.5 million barrels of oil are shipped through the strait every day -- one-third of all seaborne-traded oil, or 17 percent of the world's supply.


Any interruption in those shipments would send shock waves through the world's already-fragile economies. Already, news of Iran's unconfirmed threat has driven oil prices up $3, to more than $100 a barrel.

Theodore Karasik of the Dubai-based Institute for Near East & Gulf Military Analysis says that's nothing compared to what would happen if Iran follows through on its threat. "The consequences are that international shipping, in particular in terms of energy, would grind to a halt and this would put immense pressure on the economies all around the world," he says. "You'll see the price of oil skyrocket, probably up to $250 a barrel."

Law Of The Sea

Iran says closing the waterway is justified because governments like the United States and Britain have imposed economic sanctions on Tehran over its nuclear program, which they believe is a front for weapons development and which Tehran insists is peaceful. Iran's saber-rattling in the strait is aimed at heading off increasing efforts to curb its oil exports, and it says maritime law supports such a move.

But James Kraska, a professor of international law at the U.S. Naval War College's Center for Naval Warfare Studies, says relevant law in this case is the UN's 1982 Convention on the Law of the Sea.

"Under that convention, transit through international straits is guaranteed for all countries, so there would not be a legal basis to close the [Hormuz] Strait," he said. "And transit through the strait includes transit in the air, on the surface, as well as under the water. There's no requirement to seek the coastal states' permission, and there's no lawful basis for the coastal states to impede the transit."

Neither Iran nor the United States are among the treaty's 150 signatories, but Kraska says the convention is "customary law" that has been recognized for centuries. The waters in the strait have dual status, he says. They are technically Iranian territory, but they are also an international strait, and that gives foreign ships "a higher right of transit."

Naval Power Rules

But let's say Iran blocks it anyway. Does it have the military capacity to then take on a naval power like the United States, which is certain to respond?

A 2008 report by the Washington Institute for Near East Policy said Iran was "essentially in control of the world's oil lifeline" and had the capability to "wage unique asymmetric warfare against larger naval forces." The institute's Michael Eisenstadt says blocking the strait is "something Iran has been preparing for for years."


"Iran has been investing for decades now on creating a naval guerrilla force which would have the capability of at least interfering with shipping through the Strait of Hormuz and perhaps closing it, at least temporarily, using a combination of mines, small boats, antiship cruise missiles, submarines -- both midget submarines as well as conventional submarines -- and most recently ballistic missiles," Eisenstadt says.


Karasik of the Institute for Near East & Gulf Military Analysis agrees. "Iran's specialty is asymmetric warfare," he notes. "This is what they practice in their simulations and their exercises. This includes the use of small ships or boats, also suicide boats, underwater warfare capability, combined with the use of ballistic and cruise missiles. So they can pack a punch if they are able to get these weapons off the ground."


But like Karasik, Eisenstadt says if Iran does succeed in blocking the strait, it could only do so for about a week. "The bottom line is, although the Iranians have been talking a long time about closing the Strait of Hormuz, they probably only have the ability to do so for several days," he says. "And once the United States Navy gets involved in ensuring freedom of navigation, I think it's very clear that the outcome will be, eventually, the destruction of the Iranian Navy and the reopening of the strait."

And that may be why the threat could very well remain only that.

Written by Heather Maher, with additional reporting from Antoine Blua and Abubakar Siddique

Show comments

XS
SM
MD
LG