The Closure Iran Cannot Afford
The threat to close the Strait of Hormuz is the oldest line in Iranian deterrence. It has been recited since the Iran-Iraq War, repackaged after every sanctions tightening, and trotted out reflexively whenever a US carrier strike group enters the Gulf. The line works because the audience accepts the premise: that Iran could close the Strait if it wanted to. The premise is half true. Iran has the capability to disrupt traffic for days, possibly weeks. What it does not have is the capability to survive doing so.
Roughly twenty percent of global seaborne oil passes through Hormuz. A meaningful share of it is Iranian. Iran’s economy, already starved of foreign exchange and dependent on grey-market sales to Chinese teapot refineries, requires that its own tankers continue to move. A closure is not a closure of a corridor used by enemies. It is a closure of the only artery still feeding the regime’s hard currency reserves. Tehran cannot unilaterally exempt itself from a maritime exclusion zone enforced by mines, anti-ship missiles, and small-boat ambushes. The same threat that prices Brent at one hundred and twenty dollars also strands Iran’s December cargo at Kharg Island.
This is before the military response. The Fifth Fleet’s posture in Bahrain is calibrated for exactly this contingency. Mine countermeasures vessels, P-8s out of Al Udeid, F-15Es at Al Dhafra, and the carrier group rotating through CENTCOM are not idle. A serious closure attempt triggers a kinetic American response within forty-eight hours, and the operational record from 1988’s Praying Mantis suggests Iran’s surface navy ceases to exist within days.
Tehran knows this. The threat is preserved precisely because it is never used. Once attempted and defeated, the deterrent is gone forever, replaced by the empirical knowledge that the United States can keep the strait open. Iran’s planners prefer the productive ambiguity of a threat that markets price in but no one tests.
What Iran can do, and occasionally does, is harass. The seizure of the Stena Impero, the limpet mine attacks of the same period, the drone strikes on tankers in the Gulf of Oman: these are calibrated to remind shippers and insurers that the corridor is contested without crossing the line that triggers full retaliation. They raise insurance premiums. They do not close the strait.
The closure scenario survives in policy papers and television panels because it is convenient. It dramatizes the Iranian threat in a way that justifies budget lines and basing agreements. The actual Iranian leadership has no incentive to test it. They are not suicidal. They are, by their own lights, rational. And the most rational thing they can do with the Hormuz card is keep it in the deck, face down, forever.