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By Steve Mollman
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President Donald Trump dramatically escalated the standoff with Iran on Sunday, announcing plans to pursue a naval blockade of the Strait of Hormuz after marathon ceasefire talks ended without a deal.
Following more than 21 hours of negotiations in Islamabad, Pakistan, involving U.S., Iranian, and Pakistani officials, Vice President JD Vance confirmed early Sunday the talks had concluded with no agreement to reopen the strait or extend the fragile pause in fighting.
Within hours of the talks ending, Trump took to social media and said he had instructed the U.S. Navy to blockade “any and all ships trying to enter or leave the Strait of Hormuz” and to interdict vessels in international waters that had paid what he described as an “illegal toll” to Iran. He accused Tehran of laying mines and extorting global shipping in the narrow waterway, through which roughly 20 percent of the world’s oil typically flows, and warned that “other countries” would be involved alongside the United States.
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At the same time, Trump reiterated on Saturday his warning that foreign governments must not supply weapons to Iran, threatening severe consequences for any nation found aiding Tehran. But while the announcement signaled a decisive shift toward coercion, military experts and maritime analysts say enforcing a naval blockade of Iran would be extraordinarily difficult.
Why It Matters
A naval blockade of Iran would be among the most consequential U.S. military actions short of all-out war. It would test whether U.S. naval dominance can overcome Iran’s asymmetric approach, which is designed not to defeat American forces directly but to make shipping so dangerous that traffic slows or stops on its own.
What To Know
The timing of Trump’s move matters. The Islamabad talks—described by U.S. officials as intense and wide-ranging—were meant to address Iran’s restrictions on shipping through the strait and to extend the ceasefire. Instead, they ended after more than 21 hours with no agreement, removing the last diplomatic buffer against escalation.
Trump had previously indicated to aides he might tolerate a partial reopening of the strait as part of a deal. His announcement suggests patience with that approach has run out.
Meanwhile, Trump has warned any country supplying weapons to Tehran would face sweeping consequences, language widely interpreted as a message to Beijing and Moscow. His warning followed CNN reporting that U.S. intelligence has assessed China may be preparing to send air-defense systems to Iran—an allegation Beijing denies.
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Iran’s Threat Doesn’t Depend on Big Warships
U.S. military officials and independent analysts say American strikes have largely destroyed Iran’s conventional navy, sinking or crippling most of its large surface combatants and even an oceangoing submarine. But analysts emphasize those ships are not Iran’s primary tools for controlling the Strait of Hormuz.
Iran operates two naval forces: the regular navy and the naval arm of the Islamic Revolutionary Guard Corps (IRGC). The regular navy deploys bigger ships largely for prestige and long-range missions. The IRGC Navy is built for the confined waters of the Persian Gulf and the strait, relying on fast-attack craft, missile boats, minelayers, and drones.
Farzin Nadimi, an Iran-focused senior fellow at the Washington Institute for Near East Policy, told The Wall Street Journal more than 60 percent of the Revolutionary Guard’s fast-attack craft and speedboats remain intact despite weeks of U.S. strikes. Those vessels, he said, continue to pose a serious threat to shipping.
Geography Works in Iran’s Favor
At its narrowest point, the Strait of Hormuz is only about 20 miles wide. That geography favors Iran’s asymmetric tactics. Small IRGC boats are harder to detect than large warships and can be hidden in underground coastal pens or mixed among civilian fishing vessels.
In addition, Iran can threaten shipping from land, using truck‑mounted antiship missiles and coastal launch sites that overlook key transit lanes, allowing it to target vessels without deploying ships at all.
Maintaining constant control of waters close to Iran’s coastline would require massive, sustained U.S. resources—and even then would leave room for harassment and surprise attacks.
Mines Remain a Low-Cost, High-Impact Weapon
Naval mines are among Iran’s most effective tools and among the hardest to counter. Tehran is believed to possess thousands of mines that can be laid covertly using small craft or fishing boats. Recently, Iran warned ships to consult the Revolutionary Guard for safe routes through the strait, a move widely interpreted by analysts as a signal mines may have been deployed.
Even unconfirmed mine threats can halt traffic. Clearing mines is slow and dangerous, and new ones can be laid faster than they are removed. For shipping companies and insurers, the risk alone is often enough to suspend operations.
Drones Add Another Layer of Risk
Iran has increasingly used waterborne drones—explosive-laden unmanned boats capable of striking tankers and port facilities. Maritime security firms have documented multiple recent attacks using such systems, echoing tactics employed by Iran-backed Houthi forces in the Red Sea.
U.S. and allied security officials have previously said Tehran supplied the technology behind those drones. The ability to attack shipping remotely further complicates any attempt to enforce a blockade.
Iran Doesn’t Need to Defeat the U.S. Navy
A central weakness of the blockade idea is that Iran does not need to win a naval battle. It only needs to make shipping unsafe enough that traffic slows or stops.
With drones, mines, fast boats, and land-based missiles, Iran can continue disrupting commerce even after losing most of its large ships. Retired Vice Admiral Robert Harward, a former deputy commander of U.S. Central Command, told the Journal while Iran may have lost the bulk of its naval capacity, “the last 10% is the hardest part.”
History Explains Tehran’s Confidence
Iran’s maritime doctrine was shaped by experience. After U.S. forces destroyed much of its fleet during a one-day battle in April 1988, Tehran abandoned any effort to compete ship-for-ship. Instead, it rebuilt around asymmetrical tactics aimed at controlling commercial shipping—the vulnerability that matters most to global powers.
That doctrine remains intact today and is precisely what makes a clean, enforceable blockade so hard.
The Case for a Blockade
Some military analysts argue that a U.S.-led naval blockade of Iran could be enforced using existing American naval power already deployed in the region. Retired General Jack Keane, a former Army vice chief of staff, wrote in a New York Post column earlier this month that cutting off Iran’s oil exports through a blockade could exert decisive economic pressure without requiring a prolonged military campaign.
Others point to U.S. naval dominance. Rebecca Grant, a national security analyst at the Lexington Institute, told Just the News on Saturday that U.S. forces already have the surveillance and interdiction capability to monitor and control ship movements through the Strait of Hormuz, allowing Washington to screen or stop vessels passing through key choke points.
What Happens Next
With the talks ending without a deal, U.S. and Iranian officials are reassessing their positions as mediators search for ways to prevent further escalation. Any move to actively enforce a blockade would likely require sustained naval deployments and coordination with allies and major energy importers.
Shipping companies, insurers and energy markets are bracing for continued disruption. Even absent a fully enforced blockade, heightened U.S. enforcement and Iran’s ongoing harassment could keep traffic through the Strait of Hormuz well below normal levels, maintaining pressure on oil prices and the global economy.
Update 4/12/26, 12:32 p.m. ET: The article was updated with additional information.
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