How Would a Blockade of the Strait of Hormuz Work?

Two US Navy guided-missile destroyers conduct operations in the Strait of Hormuz on Saturday (CENTCOM)
Two US Navy guided-missile destroyers conduct operations in the Strait of Hormuz on Saturday (CENTCOM)
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How Would a Blockade of the Strait of Hormuz Work?

Two US Navy guided-missile destroyers conduct operations in the Strait of Hormuz on Saturday (CENTCOM)
Two US Navy guided-missile destroyers conduct operations in the Strait of Hormuz on Saturday (CENTCOM)

Washington: Ephrat Livni

After weekend peace talks in Pakistan between the United States and Iran ended with no agreement, President Trump on Sunday said the US Navy would impose a blockade in the Strait of Hormuz, a vital shipping waterway that Iran has mostly choked off since the war began in late February.

“Effective immediately, the United States Navy, the Finest in the World, will begin the process of BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz,” Trump said in a post on social media. “At some point, we will reach an ‘ALL BEING ALLOWED TO GO IN, ALL BEING ALLOWED TO GO OUT’ basis.”

The statement came as traffic in the strait, through which a major portion of the world’s seaborne oil and natural gas passes, has ground to a practical halt for more than a month amid Iranian strikes on commercial vessels in the region.

While Iran has allowed some ships to pass through the waterway — possibly for a fee — it has used control over the strait, including threats that it has been mined, to disrupt the global economy and to pressure the Trump administration.

The United States Central Command, known as CENTCOM, said on Sunday that a blockade would be enforced “impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman.”
Here’s what to know about the US plan for a blockade.

How might it be enforced?

American forces will not impede freedom of navigation for vessels transiting the strait to and from non-Iranian ports, CENTCOM said. The blockade will begin Monday at 10 am Eastern Time, it said.

Parties at war can exercise the right of “visit and search,” meaning that they can stop and inspect even private vessels in waters that are not neutral and decide whether or not they may pass, said James Kraska, a professor of international maritime law at the US Naval War College and a visiting professor at Harvard Law School.

A US blockade of the Strait of Hormuz would mean that any ship that attempts to transit the waterway would have to submit to a search if asked to do so and US forces would be able to determine whether or not to allow it to proceed, he said.

Such a blockade could inflict economic damage on Iran that would undermine its ability to keep fighting over the long term by denying it the ability to export oil and earn revenue. But it could also leave countries that rely on Iranian oil, like China, in a bind, Kraska said.

But there still may be mines in the strait and Iran maintains the ability to fire missiles and drones, Kraska noted.

What would a blockade mean for Iran?

A US blockade on Iranian ports would quite likely mean that Iranian vessels, which have been able to transit the Strait of Hormuz amid the war, would no longer be able to do so and that other ships that have been stuck at port or at sea could begin to move supplies in and out through this route.

This would be a reversal of the US approach so far. Even as the United States has been attacking Iran, American officials have taken steps that enabled Iranian oil to flow to limit pressure on energy prices around the world.

Last month, Scott Bessent, the Treasury secretary, said that the United States was allowing Iranian oil tankers to traverse the strait to keep up global supplies. The United States also temporarily lifted sanctions on Iranian oil at sea, allowing it to be sold to most countries, including the United States, for a month.

Some economic analysts have called on the United States to block the flow of Iranian oil as a means to end its effective control of the strait.

Robin J. Brooks, a senior fellow at the Brookings Institution, has argued that Iran’s dependence on oil exports means it will not be able to afford to keep attacking ships once its own economy takes a hit. On Sunday, he said in a post on social media that a blockade “collapses Iran’s business model.”

But Iranian officials, who have been keenly aware of the pressure on Trump as a result of spikes in energy prices, appear unconcerned. In a post on social media on Sunday, the speaker of Iran’s Parliament and the country’s top negotiator, Mohammad Bagher Ghalibaf, wrote: “Enjoy the current pump figures. With the so-called ‘blockade’, Soon you’ll be nostalgic for $4–$5 gas.”

What would the consequences be for the world?

Normally about 150 vessels transit through the Strait of Hormuz daily. In March, a little more than 150 passed through the waterway all month, according to data from S&P Global Market Intelligence. Those that did transit had made arrangements with the Iranian authorities and may have paid a toll or fee for passage, shipping intelligence firms have reported.

The halt in traffic has led to a spike in oil prices. If an American blockade on ships to and from Iran leads to freedom of navigation for vessels transiting the waterway with oil from Arabian Gulf countries, it could mean lower prices, though how quickly that could happen is not clear.
Trump said on Sunday that “any Iranian who fires at us, or at peaceful vessels, will be BLOWN TO HELL!”

But much remains unclear. Whether vessel operators will run the risk of transiting the strait at this point could depend on how Iran responds to the blockade. And whether the United States will be able to control vessel passage is also an open question.

After CENTCOM announced that it would not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports, vessel trackers expressed doubts about enforcement, pointing to tricks ships have used, like changing their identification data, to evade notice.

“This will get tricky as a number of Iran-linked tankers make bogus port calls in the region with the help of AIS spoofing,” the company Tanker Trackers posted, referring to Automatic Identification Systems. “Good luck with that, CENTCOM.”

A retired Navy admiral, James Stavridis, welcomed the blockade announcement a post on social media on Sunday. “In recent days,” he wrote, “the ONLY people benefiting from Gulf transit were the Iranians,” He said that the United States and its allies “are no worse off than we were after the Iranians started holding the Strait hostage.”

The New York Times



Iran's Top Negotiator: No US Deal Without Tangible Results

Iran's Parliament Speaker Mohammad Bagher Qalibaf, right, shakes hands with Pakistan's Army Chief Field Marshal Gen. Asim Munir during their meeting in Tehran, Iran, Sunday, May 23, 2026. (Hamed Malekpour/ICANA via AP)
Iran's Parliament Speaker Mohammad Bagher Qalibaf, right, shakes hands with Pakistan's Army Chief Field Marshal Gen. Asim Munir during their meeting in Tehran, Iran, Sunday, May 23, 2026. (Hamed Malekpour/ICANA via AP)
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Iran's Parliament Speaker Mohammad Bagher Qalibaf, right, shakes hands with Pakistan's Army Chief Field Marshal Gen. Asim Munir during their meeting in Tehran, Iran, Sunday, May 23, 2026. (Hamed Malekpour/ICANA via AP)
Iran's Parliament Speaker Mohammad Bagher Qalibaf, right, shakes hands with Pakistan's Army Chief Field Marshal Gen. Asim Munir during their meeting in Tehran, Iran, Sunday, May 23, 2026. (Hamed Malekpour/ICANA via AP)

Iran will not accept any agreement ending its conflict with the US unless there is certainty that the Iranian people's rights ⁠are secured, top negotiator ⁠Mohammad Baqer Qalibaf said on Sunday according to state media.

"There ⁠is no trust in the enemy's words and promises. Our only criterion is to achieve tangible results before we fulfill our commitments in ⁠return," ⁠he added after taking an oath as the re-elected speaker of parliament alongside its presidium.

Hours earlier, US President Donald Trump said he had secured guarantees from Iran that it would not develop nuclear weapons.

Trump has said his priorities for any deal include stopping Iran from any nuclear weapon development and re-opening the blockaded Strait of Hormuz.


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FILED - 26 May 2023, Baden-Wuerttemberg, Ueberlingen: An Iris-T missile defense system stands on the premises of Diehl Defense in Ueberlingen. Photo: Christoph Schmidt/dpa
FILED - 26 May 2023, Baden-Wuerttemberg, Ueberlingen: An Iris-T missile defense system stands on the premises of Diehl Defense in Ueberlingen. Photo: Christoph Schmidt/dpa
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FILED - 26 May 2023, Baden-Wuerttemberg, Ueberlingen: An Iris-T missile defense system stands on the premises of Diehl Defense in Ueberlingen. Photo: Christoph Schmidt/dpa
FILED - 26 May 2023, Baden-Wuerttemberg, Ueberlingen: An Iris-T missile defense system stands on the premises of Diehl Defense in Ueberlingen. Photo: Christoph Schmidt/dpa

Ukraine received a new Iris-T air defense launcher from Germany on Saturday, President Volodymyr ⁠Zelenskiy said on ⁠Sunday, asking for more ⁠provision of air defense ammunition.

"We also need missiles for air defense systems to have sufficient capabilities ⁠to ⁠repel Russian attacks," Zelenskiy said on Telegram.

On Sunday, Ukraine's military said it had struck Russia's Saratov oil refinery overnight, causing ⁠a large fire ⁠to break out at ⁠the facility.

The military said in a post on Telegram that it had also hit the ⁠Lazarevo ⁠oil pumping station in Russia's Kirov region.


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Shinjiro Koizumi, Japan's defense minister, speaks at the Shangri-La Dialogue security summit in Singapore, May 31, 2026. REUTERS/Caroline Chia
Shinjiro Koizumi, Japan's defense minister, speaks at the Shangri-La Dialogue security summit in Singapore, May 31, 2026. REUTERS/Caroline Chia
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Japan Rejects 'New Militarism,’ Accuses China of Rapidly Arming

Shinjiro Koizumi, Japan's defense minister, speaks at the Shangri-La Dialogue security summit in Singapore, May 31, 2026. REUTERS/Caroline Chia
Shinjiro Koizumi, Japan's defense minister, speaks at the Shangri-La Dialogue security summit in Singapore, May 31, 2026. REUTERS/Caroline Chia

Japan's Defense Minister Shinjiro Koizumi on Sunday rejected accusations of "new militarism" by Tokyo and criticized China for rapidly expanding its military with little transparency, underscoring mounting tensions between the two countries.

China continues to increase its defense spending at a high level, Koizumi said at the Shangri-La Dialogue in Singapore, adding: "China's external approach and military activities are matters of serious concern for Japan and the international community at the same time."

Rebutting criticism that Japan was embracing new militarism, he said: "Think about it. There's a country that has a huge arsenal of nuclear weapons and strategic bombers. Japan has neither of such ⁠weapons, and yet ⁠Japan is labelled 'new militarism'?"

Koizumi said Japan's record since World War Two "speaks for itself", citing its adherence to international law and commitment to the United Nations Charter, alongside efforts to uphold a "free and open international order."

In May, China's foreign ministry called on Asia-Pacific countries to be vigilant and "jointly resist the reckless actions of Japan's neo-militarism".

At the Singapore forum, Chinese delegate Major General Meng Xiangqing also criticized Japan.

"I deeply doubt whether ⁠a country that has not thoroughly eradicated the toxic legacy of militarism is qualified to talk extensively about defense cooperation on international occasions, and whether it can win the trust of the international community, especially the Asian countries it once invaded," he said.

Ties between Japan and China sank to their worst level in years after Japanese Prime Minister Sanae Takaichi warned in November that a hypothetical Chinese attack on Taiwan could draw a Japanese military response.

China claims Taiwan as its own territory, over the objections of Taipei's government.

Koizumi said he was "sad" he could not meet his Chinese counterpart at the dialogue, Asia's premier defense forum, but insisted Japan remains open to ⁠engagement. "We keep ⁠the door open," he said, reaffirming Japan's commitment to dialogue with China and other regional players to foster stability.

For the second year running, Chinese Defense Minister Dong Jun has given the free-wheeling Singapore security meeting a miss, skipping opportunities to meet his counterparts.

Koizumi said Japan is "determined" to play a new role in defense equipment cooperation in the Asia-Pacific and aims to tangibly strengthen deterrence in the region.

"We seek a region that can stand against coercion. We seek a region that is not misled by falsehoods. We seek a region that is not influenced by pressure," he said.

In April, Tokyo unveiled its biggest overhaul of defense export rules in decades, scrapping restrictions on overseas arms sales and opening the way for exports of warships, missiles and other weapons.