As the conflict between Israel and Iran intensifies, speculation is rising about whether the Iranians will close the Strait of Hormuz, which is critical to the world’s oil production.
The Iranian Parliament voted to close the strait following U.S. bombings on Saturday of three of Iran’s nuclear facilities: Fordow, Natanz, and Isfahan. Dubbed “Operation Midnight Hammer,” President Donald Trump hailed the military action as a “very successful attack” as it crippled Iran’s nuclear capabilities, he said in a post on X.
Although the Iranian Parliament recently voted to close the strait, the final say rests with the country’s Supreme National Security Council and Supreme Leader Ayatollah Ali Khamenei. The strait won’t be closed without their approval, and both the council and Khamenei have yet to make a decision, according to Newsweek.
As pressure in the area increases, here’s everything you need to know about the Strait of Hormuz amid the conflict and what it means for oil supply beyond the region:
What is the Strait of Hormuz?
The Strait of Hormuz is a narrow passage stretching from the Omani Musandam Peninsula to Iran, connecting the Persian Gulf to the Gulf of Oman. It’s the only way ships can get from the Persian Gulf to the Arabian Sea and, ultimately, the Indian Ocean.
Iran controls seven of the eight islands in the strait. The country has maintained a strong military presence since the 1970s, according to the Strauss Center, allowing it to have the strongest influence over the strait’s islands and waters.
Why is it important?
The strait has been deemed one of the most important passages in the world. Due to its width and depth, it is logistically capable of handling the world’s largest crude oil tankers, according to the U.S. Energy Information Administration. It’s also one of the few options for transporting oil out of the region.
The EIA calls the strait a “critical oil chokepoint.” A chokepoint is a narrow passage along a widely used waterway critical for global energy security.
Changes to its operation can be felt around the world. Even a temporary delay of oil transportation through it can cause supply shortages and increased shipping prices, leading to increased global energy prices, the EIA says.
How much oil does it transport?
About 25% of the world’s oil supply travels through the Strait of Hormuz, according to a June 2025 report from the International Energy Agency. The strait transported 20 million barrels of oil per day in 2024, the EIA reported.
The U.S. imported roughly half a million barrels of oil through the strait in 2024 — roughly 7% of all crude oil in the country, according to the EIA.
According to the Strauss Center, Iran would only need to block the passage of 4 million to 6 million barrels per day to cause a significant disruption in the world’s oil supply, but it would have to maintain this for several weeks.
What would happen if it closed?
The cost of oil per barrel would skyrocket. Immediately, oil prices could shoot up by 30% to 50%, translating to an increase in gas prices in the United States as high as $5 per gallon.
The world’s largest oil tankers can pass through the strait, which can’t be said of every oil passageway. Because of the sheer amount of oil that is transported through the strait, closing it would mean most of those shipments would have nowhere else to go, according to the EIA.
Brent crude, the international benchmark for oil prices, rose from $68.61 per barrel on June 12 to $74.36 per barrel the following morning after news of Israel’s strikes targeting Iran’s nuclear program. By June 18, it rose to $76.45.
“Closure of the Strait, even for a limited period, would have a major impact on global oil and gas markets,” EIA said.
Because much of Iran’s economy depends on foreign trade — in part, with the help of the strait — closing it would likely hurt Iran’s economy in addition to the foreign economies that depend on its oil, according to the Strauss Center.
If the Iranians went through with it, it would be “economic suicide,” said Secretary of State Marco Rubio in an appearance on Fox News on Sunday.
Some alternative pipelines exist in Saudi Arabia and the United Arab Emirates, though none can transport as much oil as the strait. Roughly 2.6 million barrels per day could be transported using these pipelines.
Has it been closed before?
The strait has never been fully closed, though the Iranians threatened to do so during the Iran-Iraq War from 1980 to 1988. The conflict, also known as the “tanker war,” involved the two countries attacking each other’s commercial vessels in the Persian Gulf and the Strait of Hormuz.
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Iran later threatened to close the strait in 2018 amid tensions with the U.S. following Trump’s withdrawal from the Iran nuclear deal and decision to reimpose the “highest level” of sanctions.
How else might oil be affected?
The closing of the strait doesn’t pose the only risk to the global oil supply. Many oil processing facilities located in the Middle East are in danger because of the conflict between Iran and Israel, CNN reported.
