Iran’s Hollow Threats to Close the Strait of Hormuz

This week, Iran has escalated a war of words over American access to the Persian Gulf and threatened to close the vital waterway to U.S. ships, in the latest example of Tehran’s blustery rhetoric about slamming the door shut on one of the world’s most important maritime choke points.

“What are you doing here? Go back to the Bay of Pigs,” Iranian Supreme Leader Ayatollah Ali Khamenei said on Monday, according to state media. On Wednesday, the deputy commander of the Islamic Revolutionary Guard Corps vowed to close the Strait of Hormuz to any “threatening” ships, signaling in particular U.S. Navy vessels that have long operated in the area and have just concluded a mine-clearing exercise there.

The Persian Gulf and the Strait of Hormuz are crucial not just to regional security, but also to the global economy. Tankers carrying about 17 million barrels of oil a day shimmy through the narrows, accounting for about one-third of all oil traded by sea globally. The strait is also a key conduit for shipments of liquefied natural gas, especially from Qatar. For countries that import oil or gas — including the United States, developed Asian economies, and increasingly, China — keeping Hormuz open to maritime traffic is crucial.

Oil generally gets more expensive when there are real or perceived threats to its supply or shipment. In recent years, the world was so glutted in oil that markets shrugged off huge risks, like the Islamic State’s rampage in Iraq, the war in Yemen, or collapsing states in Libya and Venezuela. But now that the oil market is tightening — demand is catching up to supply — such risks are increasingly unnerving. Crude oil prices rose more than 3 percent in New York and London on Thursday, especially because of wildfires in the Canadian oil patch and a deterioration in Libyan security.

The latest Iranian threats echo previous vows to close the Strait of Hormuz, such as those that spooked oil markets in early 2012. Then, however, Iran threatened to slam shut the strait to any oil tankers destined for global markets. In the end, after pushback from U.S. military and diplomatic officials — as well as a stern warning from China’s then-premier, Wen Jiabao — Iran backed off its confrontational rhetoric. It underscored how the saber-rattling is a lot easier said than done.

“Threats are easy to make,” said Anthony Cordesman, a defense analyst at the Center for Strategic and International Studies. But Iran’s naval strategy calls for deployment across the breadth of the Persian Gulf, not to bottle up vulnerable forces in a narrow body of water.

“People keep referring to ‘closing the strait.’ But we’ve got eight years of Iranian exercises that show that’s more an exercise in semantics, than the way Iran organizes to fight. Given the fact that it’s not particularly suicidal, concentrating its assets in the Strait of Hormuz makes no sense at all,” he said.

Unlike previous calls to close the strait to all shipping, the latest threats seem aimed more specifically at Washington. A leading Republican lawmaker on naval issues, Rep. Randy Forbes, introduced a resolution last month condemning Iran for its “dangerous and unprofessional behavior” in the Persian Gulf, including conducting live-fire exercises near a U.S. aircraft carrier and detaining U.S. sailors who’d veered off course earlier this year.

Forbes’s resolution directs the House to consider Tehran’s military behavior when it debates sanctions relief or the future of the deal reached last year over Iran’s nuclear weapons program. He touted the Iranian response this week as a sign that his resolution is getting under the skin of the Islamic Republic’s leaders.

The Iranian rhetoric sits uncomfortably with the Obama administration, which has made a limited rapprochement with Iran one of the centerpieces of its regional policy — not to mention its overall foreign-policy legacy — even at the risk of alienating traditional U.S. allies like Saudi Arabia. The U.S. State Department conceded that Iran’s threats to close the strait indicate that it hasn’t fundamentally changed its behavior since the nuclear deal was inked.

“Frankly, we’ve still seen Iran continue with statements and behaviors that are not helpful and not constructive,” State Department deputy spokesman Mark Toner said at a briefing on Wednesday. The nuclear deal has given the United States a better relationship with Iranian Foreign Minister Mohammad Javad Zarif, he said, “but beyond that, we’ve seen a continuance of some of the same behaviors.”

For years, defense and energy analysts have fretted over the possibility that Iran could try to choke off maritime traffic in the strait, whether through surface ships, mines, or antiship missiles. In the 1980s, during the Iran-Iraq War, both sides fought a so-called “tanker war,” targeting each other’s oil exports. That conflict eventually dragged in the United States, which protected oil tankers, but also led to several run-ins with Iranian forces, resulting in a pair of damaged U.S. Navy vessels.

Mine clearance remains a challenge for U.S. forces, which have a small number of ships that can do so. It would require the area cleared of any missile threats beforehand, meaning it would need a much broader military effort. Last month, the United States and other nations conducted a minesweeping exercise in the Persian Gulf centered on the threat posed by underwater improvised explosive devices, rather than the 5,000-odd traditional mines that Iran has in its arsenal.

“Any form of mine warfare is difficult to deal with,” Cordesman said, “and recent exercises have not been reassuring.”

But, he said, in the event of any Iranian effort to mine the Persian Gulf or block the Strait of Hormuz, Washington has a lot more tools in its arsenal than minesweepers — and that could be enough to dissuade Iran from ever seriously trying.

“They have a very good understanding of what we did to Iraq’s power grid and transportation system in 1991 with precision air power,” Cordesman said.

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