The U.S. Navy officially began a naval blockade of all Iranian ports on Monday, April 13, 2026, at 10:00 a.m. ET, as ordered by President Donald Trump. The blockade targets all maritime traffic entering and leaving Iranian ports in the Persian Gulf and Gulf of Oman, aiming to cut off Tehran's remaining oil export revenues, previously estimated at about 2 million barrels per day. In immediate market reaction, WTI crude oil jumped approximately 5% to over $94 per barrel, while Brent crude surged around 6% back above $100. Gasoline wholesale prices also rose. U.S. stock markets reflected the uncertainty: the Dow Jones Industrial Average fell 246.90 points to 47,669.67, the NYSE Composite declined 29.54 points to 22,704.96, while the Nasdaq gained 46.79 points to 22,949.69 and the S&P 500 edged up 0.67 points to 6,817.56.
Geopolitical Context and Blockade Details
The blockade follows the collapse of peace talks in Islamabad, Pakistan. President Trump announced the decision on Truth Social on April 12, accusing Iran of collecting illegal passage fees from vessels transiting the Strait of Hormuz and ordering the Navy to immediately stop any ship attempting to enter or exit. The U.S. Central Command (CENTCOM) clarified that the blockade applies to all vessels destined for or departing from Iranian ports in the Persian Gulf and Gulf of Oman, but ships transiting the strait to non-Iranian ports in the UAE, Saudi Arabia, or other Gulf states may pass freely. Prior to enforcement, additional notifications will be distributed to commercial mariners, and all vessels are instructed to monitor Notice to Mariners broadcasts and communicate with U.S. naval forces via bridge-to-bridge channel 16.
This blockade is a direct response to Iran's de facto control of the strait since the outbreak of the U.S.-Israel-Iran war on February 28, 2026. Iran had restricted traffic through the chokepoint and imposed tolls, disrupting roughly one-fifth of global oil and liquefied natural gas shipments. Iran's Islamic Revolutionary Guard Corps condemned the move as an act of piracy and illegal under international law, warning that no port in the Persian Gulf or Gulf of Oman would be safe if Iranian ports were targeted. Tehran reiterated its stance that the strait must be either open to everyone or no one, insisting that diplomacy remains the only legitimate path forward.
Market Turmoil and International Reactions
The implementation of the blockade requires a large-scale naval operation, involving multiple aircraft carrier strike groups, dozens of destroyers and frigates, and support from regional allies. Analysts highlight that the narrow waters of the Strait present real tactical risks from Iranian anti-ship missiles, drones, fast attack boats, and mines, making the operation a high-risk endeavor from day one.
International reactions have been cautious. Several Gulf nations, including Oman, and mediators expressed concern over escalation. The United Kingdom did not confirm the mine-clearing role attributed to it by Trump. European leaders avoided comments implying a full closure of the strait to all traffic. Notably, Trump also warned China on April 12 that it would face an immediate 50% tariff if caught arming Iran, as U.S. intelligence reported possible MANPADS deliveries during the ceasefire. Washington has set no end date for the blockade, stating that its duration depends on Iran's compliance and progress toward a broader diplomatic agreement. The legal status of the blockade also remains contested, with debates over whether belligerent rights apply in an armed conflict or peacetime international maritime law prevails.