WASHINGTON — The United States said it will begin blocking ships entering or leaving Iranian ports at 10 a.m. ET Monday after weekend talks with Iran in Islamabad ended without a deal, pushing oil back above $100 a barrel and shaking already fragile shipping markets, April 13, 2026. The order targets Iranian trade while allowing vessels bound for non-Iranian ports to keep moving through the Strait of Hormuz, turning a failed diplomatic push into a new economic and military pressure campaign.
In a CENTCOM press release, U.S. Central Command said the blockade would apply to vessels of all nations entering or departing Iranian ports and coastal areas on the Gulf and the Gulf of Oman. The announcement followed Reuters reporting on the failed Islamabad talks, which said the two sides remained split over Iran’s nuclear program, support for militant groups and maritime access even after the highest-level negotiations between Washington and Tehran in decades.
Iran port blockade jolts oil and shipping
A Reuters analysis of the oil-flow impact said the blockade could keep roughly 2 million barrels a day of Iranian oil out of world markets, with Iran exporting 1.84 million barrels per day in March. Before the war, roughly one-fifth of global oil and gas exports moved through the Strait of Hormuz, so even a targeted blockade carries consequences far beyond Iran’s own cargoes.
The first pressure point is Asia. China remains the main buyer of Iranian crude, and India is due to receive its first Iranian shipment in seven years, leaving refiners there especially exposed if the disruption hardens into a longer campaign.
Traders reacted fast. According to AP’s market update on oil prices, Brent crude climbed about 7% to $102.29 a barrel while U.S. crude rose about 8% to $104.24. Even before enforcement began, Reuters tracking of tanker traffic showed some ships entering the Gulf while others reversed course near the Gulf of Oman, a sign that uncertainty alone was already changing commercial behavior.
That is why the next question is not just whether the blockade starts on schedule, but how long it lasts and whether Iran chooses to challenge it directly. If enforcement expands from a narrow denial of access to Iranian ports into broader confrontations at sea, the initial price spike may not be the last.
Why the talks collapsed
The breakdown left the two sides farther apart on both substance and tone. Washington is pressing for tighter limits on Iran’s nuclear program and its regional military reach, while Tehran says the U.S. approach turned the talks into an ultimatum rather than a workable ceasefire framework.
That leaves both sides speaking the language of leverage. Washington is trying to squeeze Iran’s oil exports without formally closing the strait to everyone else. Tehran, for its part, is signaling that any attempt to enforce the new order near Hormuz could trigger retaliation. For energy markets, that combination of partial restriction, military ambiguity and public threats is often enough to keep freight moving slowly and prices moving higher.
Iran port blockade fits a longer Strait of Hormuz pattern
The current showdown did not emerge in a vacuum. Iran warned in 2011 that it could stop Gulf oil flows if sanctions widened, a reminder that Hormuz has long served as both a strategic chokepoint and a political threat. Tensions sharpened again when Tehran seized the British-flagged Stena Impero in 2019, and they resurfaced once more when Iran seized the Advantage Sweet in 2023 in the Gulf of Oman.
Those episodes did not shut the waterway for long, but they did establish the pattern now confronting traders again: maritime brinkmanship in the Gulf can move faster than diplomacy, and every new incident raises the cost of assuming the next one will stay limited. That helps explain why even a blockade written as narrowly as this one has been enough to send oil higher before the first full day of enforcement.
For now, the market is watching three uncertainties: whether U.S. forces can enforce the blockade without widening the conflict, whether Iran retaliates at sea or against regional energy infrastructure and whether diplomacy resumes before the blockade hardens into a longer campaign. Until one of those variables changes, the Strait of Hormuz is likely to remain the central risk point for global energy markets.
