The Strait of Hormuz: A U.S.-Iran Maritime Flash Point

The U.S.-Israeli war with Iran has ignited a regional conflict that is strangling shipping traffic through the Strait of Hormuz—the choke point for nearly one-fifth of the world’s oil and natural gas supply—and roiling energy markets.

After Iranian Supreme Leader Ayatollah Ali Khamenei was killed in a strike on February 28, Tehran retaliated by attacking U.S. military bases across the region and threatening ships in the Strait of Hormuz, a twenty-one-mile-wide waterway that abuts southern Iran at its narrowest point. At least three ships were targeted in the strait the day after the initial U.S.-Israeli strikes, and in the days that followed, the United States and Iran have continued to attack each others’ maritime infrastructure. Gulf countries, which rely on unimpeded travel through the strait to access global oil markets, now face shipping disruptions. Ship trafficking data showed a 70 percent drop in vessels traversing the strait after the launch of Operation Epic Fury. 

U.S.-Iran tensions had been escalating for weeks, as efforts to reach a new nuclear deal were unsuccessful. Tensions spiked when Iran temporarily closed the Strait of Hormuz to conduct live fire drills while Foreign Affairs Minister Abbas Araghchi participated in nuclear talks with the United States, raising concerns that Iran could use the strait to stymie global oil supplies in response to U.S. aggression. 

Though Iran has not formally announced the strait’s closure, authorities have reportedly warned ships not to cross the waterway as Tehran puts pressure on the strait as a point of leverage in the war. Iran claimed responsibility for attacking a ship crossing the strait on March 11, and announced that any vessel belonging to the United States, Israel, or their allies in the area were considered “legitimate targets.” Iran’s new supreme leader, Mojtaba Khamenei, announced on March 12—his first known public comments since taking over the position from his late father—that he would continue to keep the strait blocked off.  

These Iranian attacks came after the U.S. military said it had struck sixteen Iranian mine-laying ships in the waterway in what it called “the most intense day of strikes” yet on March 10. Since the war’s outbreak, the Donald Trump administration has also targeted Iran’s navy, destroying its warships and attempting to hamper its ability to fully block off the strait. Trump also said he was considering “taking over” the strait and threatened Iran against halting oil flows there. Trump has also suggested he would implement a program selling insurance for ships traveling through the Gulf to ensure “the free flow of energy to the world,” possibly via escorts from the U.S. Navy.

These escalating regional tensions have led to a surge in global oil and gas prices. In the immediate aftermath of the strikes, on March 2, Brent crude, the international oil benchmark, spiked by as much as 13 percent. Natural gas soared by 50 percent, driven in large part by gas giant Qatar Energies halting production after its facilities were targeted by Iranian drones. Inside the United States, gas prices have risen each day since the initial strikes, and crude oil prices surpassed $100 per barrel for the first time in nearly four years. Shortly after Trump said the war was “very complete,” oil prices spiraled downward again, demonstrating the volatility of the market pegged to the developments of the fighting. 

As prices fluctuate in both directions, the war has seemingly caused the largest global oil disruption in history—three times larger than the Arab oil embargo in 1973, according to Rapidan Energy Group, a DC-based independent energy market firm. Other shipping companies have diverted their vessels around the southern tip of Africa to avoid the conflict, which experts say would result in higher shipping costs and delays. 

The conflict has also renewed discussions of using emergency energy stockpiles. Members of the International Energy Agency unanimously agreed to order the release of 400 million barrels of emergency crude, its largest tranche ever and more than double the last release in the wake of Russia’s 2022 invasion of Ukraine. Aside from the United States, several Asian countries, including China, India, and Japan, rely heavily on oil that passes through the strait and are at high risk of experiencing supply disruptions. 

Iran’s use of the strait as a bargaining chip is not unprecedented. Iranian officials threatened to close the waterway in April 2019 after Trump ended sanctions waivers for importers of Iranian oil, effectively eliminating a vital source of revenue for Tehran. The United States has long considered freedom of navigation a vital interest, setting the stage for confrontation should Iran try to block shipping in the waterway. During the Iran–Iraq War, U.S. naval ships escorted oil tankers through the strait, and in 1987, U.S. forces fired on Iranian forces laying mines in the Gulf, killing four sailors.

The Iranian government has said it has the power to impose a blockade on the Strait of Hormuz. While experts say it would be difficult for Iran to close the strait for a prolonged period, Tehran has other means to disrupt global oil and gas exports—including using small boats that can interrupt shipping and submarines that can lay mines. Whether it has the right to do so is a different matter, as the UN Convention on the Law of the Sea stipulates that countries can only make sovereign decisions up to 14 miles from their coastline. Iran signed, but never ratified, the UN treaty.