Control over Strait of Hormuz will determine who wins the war

AL JEER, United Arab Emirates—Oil tankers, container ships and bulk carriers shimmer all over the horizon to the left of the windswept beach here at the entrance to the Strait of Hormuz. They have been bottled up in the Persian Gulf ever since the U.S. and Israel launched the war on Iran more than a month ago.

To the right, with the Iranian coast only 40 miles away, the dark-blue sea is completely empty. Only a handful of vessels a day manage to cross the Strait of Hormuz, down from well over a hundred before the war. They take a circuitous route through Iranian territorial waters, often paying the Iranian regime a hefty toll.

Tehran’s ability to control this international waterway, through which one-fifth of the worldwide oil supply used to pass, has become Iran’s biggest leverage against the U.S., its Gulf neighbors and the global economy. Whether the war ends in a success or defeat for Iran depends first and foremost on whether Tehran emerges from this conflict still holding the strait—and, with it, the keys to the worldwide energy markets.

“To the Iranians, the Strait of Hormuz now matters more than the nuclear program. The nuclear program was symbolic, but didn’t provide them with any deterrence,” said Vali Nasr, a professor at Johns Hopkins University and former senior State Department official who has been involved in informal discussions with Iranian representatives. “Now, the only reason why they are surviving this war is because of the strait. The Iranian thinking is that, at the end, the strait must remain under their control because it is their only deterrence and only source of revenue.”

Indeed, the Iranian regime has announced very ambitious plans for the Strait of Hormuz. The Iranian Parliament’s national-security commission has already advanced new legislation that would require passing vessels to pay for the privilege, and that would bar from the Persian Gulf any non-friendly countries. This is a lever through which Tehran hopes to force European nations, Japan and others to drop economic sanctions against it—while also permanently expelling the U.S. Navy from the Gulf’s waters.

“Trump has finally achieved his dream of regime change—but in the region’s maritime regime. The Strait of Hormuz will certainly reopen, but not for you: it will be open for those who comply with the new laws of Iran,” said the parliament commission’s chief, Ebrahim Azizi.

While Iranian officials compare the proposed toll system to the practice of the Suez Canal, which generates billions of dollars each year for Egypt, these two waterways are fundamentally different under international law. The Strait of Hormuz is a natural passage, not a man-made canal running through sovereign territory. Iran owns only one shore—with Oman’s Musandam exclave sitting on the other.

“There is no conceivable legal argument for why Iran would be able to regulate commercial shipping on Oman’s side of the maritime boundary,” said James D. Fry, an expert on international maritime law and professor at the University of Hong Kong Faculty of Law.

President Trump has sent mixed signals about his intentions. In his speech on Wednesday, he said the U.S. doesn’t import oil from the Gulf, and that those nations that do—in Europe and Asia—should be the ones reopening the Strait of Hormuz. “They must grab it and cherish it. They can do it easily,” he said. In any event, he added, once the war is over, “the strait will open up naturally.”

Hours earlier, in a Truth Social post, Trump also said the U.S. will be blasting Iran into oblivion until the strait “is open, free and clear.” He has already dispatched thousands of Marines and soldiers to the Middle East, units that could be used in a ground operation to force the reopening of the strait. Any such operation, if ordered, would risk significant casualties, considering that Iran relies on drones, missiles and small speedboats to strike vessels that attempt to defy its blockade.

Ending the war in the near future while Iran still controls the crucial waterway would be a geopolitical disaster for America’s allies and partners in the Middle East and beyond, said Hasan Alhasan, a senior fellow at the International Institute for Strategic Studies and a former national-security official in Bahrain.

“Iran would be able to enforce selective sanctions on whomever it wants and whenever it wants, and essentially hold the flow of shipping through the strait at risk if it desires to do so,” Alhasan said. “This would ensure indefinite Iranian leverage over the Gulf states’ economies and over global energy security, and it would leave Iran in a state in which it is still capable of posing a threat, wounded, embittered, and in a hostile posture vis-à-vis most countries in the region.”

Gulf states have attempted to mitigate the impact of the strait’s closure. Saudi Arabia has redirected part of its oil exports via a pipeline to the Red Sea port of Yanbu. The U.A.E. is shipping its oil to the port of Fujairah on the Gulf of Oman, a vast complex of oil and gas storage facilities that continue filling tankers despite fires caused by Iranian drone attacks in the early days of the war. Lines of idling trucks stretch several miles to the nearby U.A.E. port of Khorfakkan, which is picking up shipments that can’t reach Dubai anymore.

In U.A.E. villages near the Strait of Hormuz, such as Al Jeer, new posters show the Gulf monarchy’s ruler flanked by troops, jet fighters and helicopters. The statement “I have strengthened you in the name of God, oh Homeland,” is on billboards hanging from many homes.

So far, European and Asian nations have shown little appetite to join any U.S. military effort to reopen the Strait of Hormuz. French President Emmanuel Macron Thursday said a military option in the Hormuz is unrealistic, and freedom of navigation in the waterway can only be re-established through coordination with Iran.

Gulf Cooperation Council states such as the U.A.E. and Saudi Arabia possess significant naval and air forces of their own. But they, too, would be unlikely to fight Iran for the strait absent a major American intervention, diplomats and officials say.

Still—together with other regional parties, such as Turkey, Egypt and Pakistan, and the blessing of much of the international community—these Gulf states could apply significant political and economic pressure on the Iranian regime to reopen the waterway for free passage. Even Russia, Iran’s closest ally, said this week that any arrangements for the Strait of Hormuz must be agreed by all the other littoral states of the Gulf.

Iran trying to enforce its control over the Strait of Hormuz once hostilities end would be akin to piracy, said Mehran Haghirian, director of research at the Bourse & Bazaar think tank. “It would just lead to a complete isolation of the Islamic Republic beyond what it is right now. And in what world would the GCC states just sit back and allow their lifeline to be controlled by Iran?” he said. “The tension would be not just with the GCC states but with the entire international community, from Indonesia to Burkina Faso to Colombia, that all depend in one way or another on the Strait of Hormuz.”

There is another, more practical, difficulty: Currently, Iran’s Islamic Revolution Guard Corps is considered a terrorist organization by many states, including the U.S. and members of the European Union. Financial transactions with Iran, including paying for the passage of Hormuz, are subject to U.S. sanctions that would deter major global shipping companies.

“In this bizarre era of maritime protection money, shipowners will risk their ship if they don’t pay Iran—but if they pay Iran, they risk their future in the global financial system,” said Jason Chuah, professor of maritime law at the City University of London. “What the Iranians are asking for is not just a transit fee but a loyalty test. It’s a test that no commercial entity can hope to pass.”

Write to Yaroslav Trofimov at yaroslav.trofimov@wsj.com