Key keywords: Strait of Hormuz shipping transit, US-Iran preliminary agreement, stranded commercial vessels, global crude oil supply, Persian Gulf maritime security, international shipping logistics, Middle East geopolitical de-escalation, oil tanker congestion More than 270 stranded commercial vessels, including 120 oil tankers carrying a combined 18 million barrels of crude and refined petroleum products, began orderly transit through the Strait of Hormuz on Thursday, 48 hours after Washington and Tehran announced a preliminary, Oman-mediated de-escalation deal aimed at reducing tensions in the world’s busiest energy shipping corridor. For nearly three weeks, escalating tit-for-tat actions between the U.S. and Iran, including Iranian seizures of two U.S.-linked cargo ships and new U.S. sanctions targeting Iranian maritime logistics networks, had led to a near shutdown of unapproved transit through the 21-mile-wide chokepoint, which handles roughly 20% of all seaborne crude oil traded globally. Hundreds of ships had anchored in the Gulf of Oman and Persian Gulf waiting for clearance, with daily demurrage costs for large tankers surging to $120,000 per vessel, and global Brent crude prices rising 11% over the period on supply disruption fears. The preliminary deal, details of which remain partially undisclosed, includes commitments from both sides to pause hostile actions targeting commercial shipping in the region. Iran has agreed to release three previously detained foreign-flagged tankers with no links to sanctioned cargo, and to grant immediate transit clearance to all non-sanctioned commercial vessels. The U.S. has in turn agreed to suspend a planned new round of sanctions targeting Iran’s oil export shipping infrastructure, and to reduce the frequency of U.S. Coast Guard intercepts of Iranian civilian vessels in international waters in the Gulf. Representatives from the International Maritime Organization (IMO) confirmed on Thursday that transit times through the strait have already returned to pre-crisis levels of 8 to 12 hours, down from a peak of 14 days of waiting time earlier this week. Major global shipping lines including Maersk, MSC and COSCO have all issued internal notices resuming regular scheduled services through the strait, ending three weeks of rerouting around the Cape of Good Hope that added 12 to 18 days of transit time and 30% to shipping costs for Asia-Europe and Asia-U.S. East Coast energy and cargo routes. IEA officials noted that the resumption of shipping has already pushed Brent crude futures down 4.7% in early trading on Thursday, easing fears of a global energy supply crunch heading into the northern hemisphere winter. Both U.S. and Iranian officials have confirmed that follow-up negotiations will be held in Muscat next month to expand the preliminary deal into a longer-term maritime security framework for the region.