The waiver marks a sharp pivot not only for Trump but also for the decades-old sanctions regime the U.S. has levied against the country.

Iranian supertankers have switched on their transponders, after going dark during the war, as they depart the region loaded with oil.

Washington has granted Iran a 60-day waiver on oil sanctions, permitting the nation to produce, export, and sell its crude until August 21. This move, part of an interim deal to…