^{A woman walks past a mural in Tehran depicting what the regime believes is its ability to target US naval vessels in the Strait of Hormuz}

Strait of Hor­muz hands Tehran new power
Islamic repub­lic sees con­trol of water­way cru­cial to global trade as potent stra­tegic tool

NAJMEH BOZORGMEHR — TEHRAN 18-04-2026 FT

For dec­ades, Iran hin­ted that it could close the Strait of Hor­muz if hos­til­it­ies between the US, Israel or its regional rivals boiled over. Yet the ease with which it has finally done so sur­prised not only its rivals but mem­bers of the regime itself.

While regional ten­sions have long centred on Iran’s nuc­lear or mis­sile pro­grammes, this pre­vi­ously untested weapon has become its most import­ant point of lever­age, trig­ger­ing the biggest energy crisis in dec­ades and deal­ing an imme­di­ate hit to the global eco­nomy.

One per­son close to the regime described the clos­ure as a stra­tegic break­through for the Islamic repub­lic, which had before the US-Israeli war been seen to be at its weak­est point mil­it­ar­ily in years.

“It feels like hav­ing an atomic bomb,” the per­son said, adding that enfor­cing the clos­ure has been “easier than expec­ted” and claim­ing it would not be reversed “under any cir­cum­stances”.

For US Pres­id­ent Don­ald Trump, the devel­op­ment presents an unex­pec­ted chal­lenge. Hav­ing gone to war with hopes of everything from top­pling the regime to pre­vent­ing Iran acquir­ing nuc­lear weapons — something Tehran has long denied it is plan­ning — Wash­ing­ton is now grap­pling with a prob­lem that did not exist before.

In a sign of Trump’s frus­tra­tion, he ordered the US Navy to block­ade the strait, through which roughly a fifth of the world’s energy sup­plies transit. This is designed to pre­vent ships trav­el­ling to and from Ira­nian ports and cut off Iran’s oil exports, intensi­fy­ing pres­sure on Tehran to nego­ti­ate a deal to end the war and reopen the water­way.

But Iran’s top mil­it­ary com­mand centre threatened on Wed­nes­day to use the coun­try’s “full force” to stop trade not only in the Gulf but also the Red Sea and Gulf of Oman if the block­ade con­tin­ued.

Yes­ter­day Iran’s for­eign min­is­ter announced that the Strait of Hor­muz was “com­pletely open” to com­mer­cial ship­ping for the dur­a­tion of the 10-day cease­fire in Lebanon, fol­low­ing the agree­ment between Israel and Hizbol­lah on Thursday.

But Iran would still insist mer­chant ves­sels require per­mis­sion from the Islamic Revolu­tion­ary Guard Corps before trans­it­ing the strait, an unnamed Ira­nian offi­cial told state tele­vi­sion.

Ira­nian politi­cians have artic­u­lated a more expans­ive vis­ion of the eco­nomic and polit­ical role they hope the strait will play in the coun­try’s future.

Iran has pre­vi­ously said that it expects oil tankers trans­it­ing the strait to pay up to $2mn in crypto­cur­rency, and its par­lia­ment is draft­ing legis­la­tion to reg­u­late mari­time pas­sage, intro­du­cing tolls and restrict­ing access for ves­sels linked to “hos­tile states”.

Some Ira­nian mem­bers of par­lia­ment have sug­ges­ted Tehran needs the rev­en­ues to com­pensate for the costs of war.

Hamid-Reza Hajibabaei, Iran’s deputy par­lia­ment Speaker, told state tele­vi­sion that the water­way had turned into the coun­try’s top point of lever­age.

“When we have con­trol over the Strait of Hor­muz, no other coun­try can impose sanc­tions on us,” he claimed, in a ref­er­ence to dec­ades of US-led eco­nomic pen­al­ties.

Before the US block­ade, Tehran’s oil rev­en­ues nearly doubled as the coun­try con­tin­ued to export oil, much of it destined for China, accord­ing to Ira­nian ana­lysts. But the war and Iran’s decision to close the strait have come at a con­sid­er­able cost to the regime.

US and Israeli air strikes on indus­trial facil­it­ies have caused tens of bil­lions of dol­lars in dam­age. The pro­spect that Iran could con­tinue levy­ing tolls has caused alarm around the world. It could hurt not only neigh­bour­ing states but also import­ant eco­nomic part­ners such as China.

“When it comes to apply­ing pres­sure, the Ira­ni­ans have shown they can asym­met­ric­ally do so very effect­ively, very quickly, with rel­at­ively little mil­it­ary cost,” said HA Hellyer, a senior asso­ciate fel­low at the Royal United Ser­vices Insti­tute think-tank. “But in so doing, they’ve wrecked their con­nec­tions with pretty much the whole Gulf Arab region.”

Along­side the fraught and long­stand­ing efforts to make a deal curb­ing Iran’s nuc­lear pro­gramme, con­vin­cing Tehran to allow the free flow of ship­ping through the strait has become a cent­ral stick­ing point in talks between the US and Iran.

Gulf states fear the US could agree a deal that allows Iran to retain some degree of con­trol over the strait.

The Islamic repub­lic has con­tin­ued to project defi­ance over Trump’s block­ade, but ana­lysts say it may have to start sig­ni­fic­antly redu­cing oil pro­duc­tion within a fort­night if the block­ade suc­ceeds in stop­ping its exports.

Tehran has sig­nalled it could seek to escal­ate. Regime fig­ures have sug­ges­ted the Red Sea choke­point Bab al-Mandab could be tar­geted by Iran-backed Houthis, who caused havoc to mari­time trade by fir­ing mis­siles at ships in the con­flict that fol­lowed Hamas’s Octo­ber 7 2023 attack on Israel.

Even if the block­ade could do sig­ni­fic­ant dam­age to Iran’s eco­nomy, sup­port­ers of the regime sug­ges­ted the Islamic repub­lic would have a higher tol­er­ance for pain than Trump, who is under pres­sure to con­tain the domestic eco­nomic fal­lout ahead of US midterm elec­tions in Novem­ber.

Accord­ing to indi­vidu­als close to the lead­er­ship, the decision to close the strait gained momentum after Israel’s 12-day war on Iran in June.

The strait is a crit­ical artery not only for energy but also global sup­ply chains. Ali Shir­in­zad, a mem­ber of par­lia­ment, said on Monday that Ira­nian duties would apply not only to oil tankers but to “any ves­sels”.

Hard­liners in Tehran have framed the clos­ure of the strait as a turn­ing point. Even mod­er­ate fig­ures are resigned to Iran seek­ing to retain lever­age over the strait. Majid Hos­seini, a reform­ist polit­ical eco­nom­ist at Tehran uni­versity, said there was little pro­spect of Iran back­ing down. “This is the main and per­haps the only deterrent lever­age the Islamic repub­lic now has that is work­ing.”