According to Trump and HMM, an Iranian attack on the Korean cargo ship HMM NAMU caused an explosion and fire in the Strait of Hormuz on May 4 at 8:40 PM KST. The vessel's engine room caught fire, which crew members extinguished using carbon dioxide after about four hours. Trump stated on Truth Social that Iran had fired at unrelated nations' vessels, including Korean cargo ships, in connection with the U.S. military's "Liberation Project" operation to open the strait. He urged South Korea to join the operation.
The incident coincided with renewed Iranian attacks on the region. The UAE Defense Ministry announced it intercepted 19 missiles and drones launched from Iran, with fires breaking out at the Fujairah petrochemical complex. The U.S. military reported sinking seven Iranian vessels during the operation to escort commercial shipping through the strait.