U.S. naval blockade begins

A United States naval blockade of traffic tied to Iranian ports took effect on April 13, opening a new front in the seven-week U.S.-Iran war. (cnn.com) President Donald Trump said the blockade would begin at 10:00 a.m. Eastern time on Monday, April 13, and apply to ships entering or leaving Iranian ports. He also warned that Iranian vessels approaching the blockade line would be “eliminated,” according to multiple live updates and wire reports. (cbsnews.com) (cnbc.com) The policy was announced after U.S.-Iran peace talks in Islamabad ended without an agreement. NPR reported that U.S. forces would also interdict vessels accused of paying what Washington called an “illegal toll” to Iran. (npr.org) (usatoday.com) A blockade is a military effort to stop ships from moving in or out of a coast or port. In this case, the United States is using naval power to choke off maritime traffic linked to Iran’s main export routes and port access. (britannica.com) (cnbc.com) The order reaches beyond one harbor because Iran sits on the Strait of Hormuz, the narrow waterway between the Persian Gulf and the Gulf of Oman. That channel handles a large share of the world’s seaborne oil trade, so any military disruption there can hit shipping costs and crude prices within hours. (britannica.com) (time.com) The blockade follows Operation Epic Fury, the U.S. campaign that the Defense Department says began at 1:15 a.m. on February 28, 2026. A Pentagon fact sheet dated April 1 said the operation had involved more than 13,000 combat flights and damaged or destroyed more than 155 Iranian vessels. (defense.gov) Trump has framed the blockade as a response to Iran’s pressure on commercial shipping and what he called extortion in the strait. Politico reported that allies and U.S. officials were still trying to understand how the blockade would be enforced and how far it would extend. (cnbc.com) (politico.com) Iran has not accepted the U.S. terms that emerged from the Islamabad talks, and Bloomberg reported that both sides were still weighing another round of negotiations even as the blockade started. That left diplomacy and military escalation moving at the same time on April 13. (bloomberg.com) (time.com) Oil prices jumped after the talks failed and the blockade threat became policy, according to USA Today. The next test is whether commercial shippers reroute, pause sailings, or keep moving under U.S. warning. (usatoday.com)